Interlaced scan patterns for lidar system

ABSTRACT

In one embodiment, a lidar system includes a light source configured to emit pulses of light and a scanner configured to scan at least a portion of the emitted pulses of light along an interlaced scan pattern. The scanner includes a first scanning mirror configured to scan the portion of the emitted pulses of light substantially parallel to a first scan axis to produce multiple scan lines of the interlaced scan pattern, where each scan line is oriented substantially parallel to the first scan axis. The scanner also includes a second scanning mirror configured to distribute the scan lines along a second scan axis that is substantially orthogonal to the first scan axis, where the scan lines are distributed in an interlaced manner.

PRIORITY

This application claims the benefit, under 35 U.S.C. § 119(e), of U.S.Provisional Patent Application No. 62/569,991, filed 9 Oct. 2017, whichis incorporated herein by reference.

TECHNICAL FIELD

This disclosure generally relates to lidar systems.

BACKGROUND

Light detection and ranging (lidar) is a technology that can be used tomeasure distances to remote targets. Typically, a lidar system includesa light source and an optical receiver. The light source can be, forexample, a laser which emits light having a particular operatingwavelength. The operating wavelength of a lidar system may lie, forexample, in the infrared, visible, or ultraviolet portions of theelectromagnetic spectrum. The light source emits light toward a targetwhich then scatters the light. Some of the scattered light is receivedback at the receiver. The system determines the distance to the targetbased on one or more characteristics associated with the returned light.For example, the system may determine the distance to the target basedon the time of flight of a returned light pulse.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example light detection and ranging (lidar)system.

FIG. 2 illustrates an example scan pattern produced by a lidar system.

FIG. 3 illustrates an example lidar system with an example overlapmirror.

FIG. 4 illustrates an example lidar system with an example rotatingpolygon mirror.

FIG. 5 illustrates an example light-source field of view and receiverfield of view for a lidar system.

FIG. 6 illustrates an example scan pattern that includes multiple scanlines and multiple pixels.

FIG. 7 illustrates an example scan pattern with a substantially uniformdistribution of scan lines.

FIG. 8 illustrates an example scan pattern with a nonuniformdistribution of scan lines.

FIG. 9 illustrates an example focused scan pattern.

FIG. 10 illustrates an example scan pattern with a substantially uniformdistribution of scan lines.

FIG. 11 illustrates an example scan pattern with a nonuniformdistribution of scan lines.

FIG. 12 illustrates an example scan pattern contained within anadjustable field of regard.

FIG. 13 illustrates an example focused scan pattern with slightly curvedscan lines.

FIG. 14 illustrates an example nonuniform scan pattern with scan linesoriented vertically.

FIG. 15 illustrates an example focused scan pattern with scan linesoriented vertically.

FIG. 16 illustrates an example scan profile for a scan pattern with asubstantially uniform distribution of scan lines.

FIG. 17 illustrates an example scan profile for a scan pattern with anonuniform distribution of scan lines.

FIG. 18 illustrates an example scan profile associated with a focusedscan pattern.

FIG. 19 illustrates an example scan profile and a corresponding angularscanning-speed curve.

FIG. 20 illustrates an example dual-direction scan profile.

FIGS. 21-23 each illustrate an example vehicle with a lidar systemconfigured to produce a particular scan pattern.

FIGS. 24-25 each illustrate an example scan pattern to which one or moreangular offsets are applied.

FIG. 26 illustrates an example scan pattern with 16 scan lines.

FIGS. 27-28 each illustrate one part of an example 2-fold interlacedscan pattern.

FIGS. 29-32 each illustrate one part of an example 4-fold interlacedscan pattern.

FIG. 33 illustrates an example method for scanning along an interlacedscan pattern.

FIG. 34 illustrates an example computer system.

DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 illustrates an example light detection and ranging (lidar) system100. In particular embodiments, a lidar system 100 may be referred to asa laser ranging system, a laser radar system, a LIDAR system, a lidarsensor, or a laser detection and ranging (LADAR or ladar) system. Inparticular embodiments, a lidar system 100 may include a light source110, mirror 115, scanner 120, receiver 140, or controller 150. The lightsource 110 may include, for example, a laser which emits light having aparticular operating wavelength in the infrared, visible, or ultravioletportions of the electromagnetic spectrum. As an example, light source110 may include a laser with an operating wavelength betweenapproximately 1.2 μm and 1.7 μm. The light source 110 emits an outputbeam of light 125 which may be continuous-wave (CW), pulsed, ormodulated in any suitable manner for a given application. The outputbeam of light 125 is directed downrange toward a remote target 130. Asan example, the remote target 130 may be located a distance D ofapproximately 1 m to 1 km from the lidar system 100.

Once the output beam 125 reaches the downrange target 130, the targetmay scatter or reflect at least a portion of light from the output beam125, and some of the scattered or reflected light may return toward thelidar system 100. In the example of FIG. 1, the scattered or reflectedlight is represented by input beam 135, which passes through scanner 120and is directed by mirror 115 to receiver 140. In particularembodiments, a relatively small fraction of the light from output beam125 may return to the lidar system 100 as input beam 135. As an example,the ratio of input beam 135 average power, peak power, or pulse energyto output beam 125 average power, peak power, or pulse energy may beapproximately 10⁻¹, 10⁻², 10⁻³, 10⁻⁴, 10⁻⁵, 10⁻⁶, 10⁻⁷, 10⁻⁸, 10⁻⁹,10⁻¹⁰, 10⁻¹¹, or 10⁻¹². As another example, if a pulse of output beam125 has a pulse energy of 1 microjoule (μJ), then the pulse energy of acorresponding pulse of input beam 135 may have a pulse energy ofapproximately 10 nanojoules (nJ), 1 nJ, 100 picojoules (pJ), 10 pJ, 1pJ, 100 femtojoules (fJ), 10 fJ, 1 fJ, 100 attojoules (aJ), 10 aJ, 1 aJ,or 0.1 aJ. In particular embodiments, output beam 125 may be referred toas a laser beam, light beam, optical beam, emitted beam, or beam. Inparticular embodiments, input beam 135 may be referred to as a returnbeam, received beam, return light, received light, input light,scattered light, or reflected light. As used herein, scattered light mayrefer to light that is scattered or reflected by a target 130. As anexample, an input beam 135 may include: light from the output beam 125that is scattered by target 130; light from the output beam 125 that isreflected by target 130; or a combination of scattered and reflectedlight from target 130.

In particular embodiments, receiver 140 may receive or detect photonsfrom input beam 135 and generate one or more representative signals. Forexample, the receiver 140 may generate an output electrical signal 145that is representative of the input beam 135. This electrical signal 145may be sent to controller 150. In particular embodiments, controller 150may include a processor, computing system (e.g., an ASIC or FPGA), orother suitable circuitry configured to analyze one or morecharacteristics of the electrical signal 145 from the receiver 140 todetermine one or more characteristics of the target 130, such as itsdistance downrange from the lidar system 100. This can be done, forexample, by analyzing the time of flight or phase modulation for a beamof light 125 transmitted by the light source 110. If lidar system 100measures a time of flight of T (e.g., T represents a round-trip time offlight for an emitted pulse of light to travel from the lidar system 100to the target 130 and back to the lidar system 100), then the distance Dfrom the target 130 to the lidar system 100 may be expressed as D=c·T/2,where c is the speed of light (approximately 3.0×10⁸ m/s). As anexample, if a time of flight is measured to be T=300 ns, then thedistance from the target 130 to the lidar system 100 may be determinedto be approximately D=45.0 m. As another example, if a time of flight ismeasured to be T=1.33 μs, then the distance from the target 130 to thelidar system 100 may be determined to be approximately D=199.5 m. Inparticular embodiments, a distance D from lidar system 100 to a target130 may be referred to as a distance, depth, or range of target 130. Asused herein, the speed of light c refers to the speed of light in anysuitable medium, such as for example in air, water, or vacuum. As anexample, the speed of light in vacuum is approximately 2.9979×10⁸ m/s,and the speed of light in air (which has a refractive index ofapproximately 1.0003) is approximately 2.9970×10⁸ m/s.

In particular embodiments, light source 110 may include a pulsed laser.As an example, light source 110 may be a pulsed laser configured toproduce or emit pulses of light with a pulse duration or pulse width ofapproximately 10 picoseconds (ps) to 100 nanoseconds (ns). The pulsesmay have a pulse duration of approximately 100 ps, 200 ps, 400 ps, 1 ns,2 ns, 5 ns, 10 ns, 20 ns, 50 ns, 100 ns, or any other suitable pulseduration. As another example, light source 110 may be a pulsed laserthat produces pulses with a pulse duration of approximately 1-5 ns. Asanother example, light source 110 may be a pulsed laser that producespulses at a pulse repetition frequency of approximately 100 kHz to 5 MHzor a pulse period (e.g., a time between consecutive pulses) ofapproximately 200 ns to 10 μs. In particular embodiments, light source110 may have a substantially constant pulse repetition frequency, orlight source 110 may have a variable or adjustable pulse repetitionfrequency. As an example, light source 110 may be a pulsed laser thatproduces pulses at a substantially constant pulse repetition frequencyof approximately 640 kHz (e.g., 640,000 pulses per second),corresponding to a pulse period of approximately 1.56 μs. As anotherexample, light source 110 may have a pulse repetition frequency that canbe varied from approximately 500 kHz to 3 MHz. As used herein, a pulseof light may be referred to as an optical pulse, a light pulse, or apulse.

In particular embodiments, light source 110 may produce a pulsed or CWfree-space output beam 125 having any suitable average optical power. Asan example, output beam 125 may have an average power of approximately 1milliwatt (mW), 10 mW, 100 mW, 1 watt (W), 10 W, or any other suitableaverage power. In particular embodiments, output beam 125 may includeoptical pulses with any suitable pulse energy or peak optical power. Asan example, output beam 125 may include pulses with a pulse energy ofapproximately 0.01 μJ, 0.1 μJ, 1 μJ, 10 μJ, 100 μJ, 1 mJ, or any othersuitable pulse energy. As another example, output beam 125 may includepulses with a peak power of approximately 10 W, 100 W, 1 kW, 5 kW, 10kW, or any other suitable peak power. The peak power (P_(peak)) of apulse of light can be related to the pulse energy (E) by the expressionE=P_(peak)·Δt, where Δt is the duration of the pulse, and the durationof a pulse may be defined as the full width at half maximum duration ofthe pulse. For example, an optical pulse with a duration of 1 ns and apulse energy of 1 μJ has a peak power of approximately 1 kW. The averagepower (P_(av)) of an output beam 125 can be related to the pulserepetition frequency (PRF) and pulse energy by the expressionP_(av)=PRF·E. For example, if the pulse repetition frequency is 500 kHz,then the average power of an output beam 125 with 1 μJ pulses isapproximately 0.5 W.

In particular embodiments, light source 110 may include a laser diode,such as for example, a Fabry-Perot laser diode, a quantum well laser, adistributed Bragg reflector (DBR) laser, a distributed feedback (DFB)laser, or a vertical-cavity surface-emitting laser (VCSEL). As anexample, light source 110 may include an aluminum-gallium-arsenide(AlGaAs) laser diode, an indium-gallium-arsenide (InGaAs) laser diode,an indium-gallium-arsenide-phosphide (InGaAsP) laser diode, or a laserdiode that includes any suitable combination of aluminum (Al), indium(In), gallium (Ga), arsenic (As), phosphorous (P), or any other suitablematerial. In particular embodiments, light source 110 may include apulsed laser diode with a peak emission wavelength between 1400 nm and1600 nm. As an example, light source 110 may include a current-modulatedInGaAsP DFB laser diode that produces optical pulses at a wavelength ofapproximately 1550 nm.

In particular embodiments, light source 110 may include a pulsed or CWlaser diode followed by one or more optical-amplification stages. As anexample, light source 110 may be a fiber-laser module that includes a CWor current-modulated laser diode with an operating wavelength ofapproximately 1550 nm followed by a single-stage or a multi-stageerbium-doped fiber amplifier (EDFA). As another example, light source110 may include a continuous-wave (CW) or quasi-CW laser diode followedby an external optical modulator (e.g., an electro-optic amplitudemodulator), and the output of the modulator may be fed into an opticalamplifier. As another example, light source 110 may include a pulsed orCW laser diode followed by a semiconductor optical amplifier (SOA). TheSOA may include an active optical waveguide configured to receive lightfrom the laser diode and amplify the light as it propagates through thewaveguide. The SOA may be integrated on the same chip as the laserdiode, or the SOA may be a separate device with an anti-reflectioncoating on its input facet or output facet. In particular embodiments,light source 110 may include a laser diode which produces optical pulsesthat are not amplified by an optical amplifier. As an example, a laserdiode (which may be referred to as a direct emitter or a direct-emitterlaser diode) may emit optical pulses that form an output beam 125 thatis directed downrange from a lidar system 100. A light source 110 thatincludes a direct-emitter laser diode may not include an opticalamplifier, and the optical pulses produced by a direct emitter may notbe amplified. A direct-emitter laser diode may be driven by anelectrical power source that supplies current pulses to the laser diode,and each current pulse may result in the emission of an output opticalpulse.

In particular embodiments, an output beam of light 125 emitted by lightsource 110 may be a collimated optical beam having any suitable beamdivergence, such as for example, a full-angle beam divergence ofapproximately 0.5 to 10 milliradians (mrad). A divergence of output beam125 may refer to an angular measure of an increase in beam size (e.g., abeam radius or beam diameter) as output beam 125 travels away from lightsource 110 or lidar system 100. In particular embodiments, output beam125 may have a substantially circular cross section with a beamdivergence characterized by a single divergence value. As an example, anoutput beam 125 with a circular cross section and a full-angle beamdivergence of 2 mrad may have a beam diameter or spot size ofapproximately 20 cm at a distance of 100 m from lidar system 100. Inparticular embodiments, output beam 125 may have a substantiallyelliptical cross section characterized by two divergence values. As anexample, output beam 125 may have a fast axis and a slow axis, where thefast-axis divergence is greater than the slow-axis divergence. Asanother example, output beam 125 may be an elliptical beam with afast-axis divergence of 4 mrad and a slow-axis divergence of 2 mrad.

In particular embodiments, an output beam of light 125 emitted by lightsource 110 may be unpolarized or randomly polarized, may have nospecific or fixed polarization (e.g., the polarization may vary withtime), or may have a particular polarization (e.g., output beam 125 maybe linearly polarized, elliptically polarized, or circularly polarized).As an example, light source 110 may produce linearly polarized light,and lidar system 100 may include a quarter-wave plate that converts thislinearly polarized light into circularly polarized light. The circularlypolarized light may be transmitted as output beam 125, and lidar system100 may receive input beam 135, which may be substantially or at leastpartially circularly polarized in the same manner as the output beam 125(e.g., if output beam 125 is right-hand circularly polarized, then inputbeam 135 may also be right-hand circularly polarized). The input beam135 may pass through the same quarter-wave plate (or a differentquarter-wave plate) resulting in the input beam 135 being converted tolinearly polarized light which is orthogonally polarized (e.g.,polarized at a right angle) with respect to the linearly polarized lightproduced by light source 110. As another example, lidar system 100 mayemploy polarization-diversity detection where two polarizationcomponents are detected separately. The output beam 125 may be linearlypolarized, and the lidar system 100 may split the input beam 135 intotwo polarization components (e.g., s-polarization and p-polarization)which are detected separately by two photodiodes (e.g., a balancedphotoreceiver that includes two photodiodes).

In particular embodiments, lidar system 100 may include one or moreoptical components configured to condition, shape, filter, modify,steer, or direct the output beam 125 or the input beam 135. As anexample, lidar system 100 may include one or more lenses, mirrors,filters (e.g., bandpass or interference filters), beam splitters,polarizers, polarizing beam splitters, wave plates (e.g., half-wave orquarter-wave plates), diffractive elements, or holographic elements. Inparticular embodiments, lidar system 100 may include a telescope, one ormore lenses, or one or more mirrors configured to expand, focus, orcollimate the output beam 125 or the input beam 135 to a desired beamdiameter or divergence. As an example, the lidar system 100 may includeone or more lenses to focus the input beam 135 onto an active region ofa photodetector of receiver 140. As another example, the lidar system100 may include one or more flat mirrors or curved mirrors (e.g.,concave, convex, or parabolic mirrors) to steer or focus the output beam125 or the input beam 135. For example, the lidar system 100 may includean off-axis parabolic mirror to focus the input beam 135 onto an activeregion of receiver 140. As illustrated in FIG. 1, the lidar system 100may include mirror 115 (which may be a metallic or dielectric mirror),and mirror 115 may be configured so that light beam 125 passes throughthe mirror 115 or passes along an edge or side of the mirror 115. As anexample, mirror 115 (which may be referred to as an overlap mirror,superposition mirror, or beam-combiner mirror) may include a hole, slot,or aperture which output light beam 125 passes through. As anotherexample, mirror 115 may be configured so that at least 80% of outputbeam 125 passes through mirror 115 and at least 80% of input beam 135 isreflected by mirror 115. In particular embodiments, mirror 115 mayprovide for output beam 125 and input beam 135 to be substantiallycoaxial so that the two beams travel along substantially the sameoptical path (albeit in opposite directions).

In particular embodiments, lidar system 100 may include a scanner 120 tosteer the output beam 125 in one or more directions downrange. As anexample, scanner 120 may include one or more scanning mirrors that areconfigured to rotate, oscillate, tilt, pivot, or move in an angularmanner about one or more axes. In particular embodiments, a flatscanning mirror may be attached to a scanner actuator or mechanism whichscans the mirror over a particular angular range. As an example, scanner120 may include a galvanometer scanner, a resonant scanner, apiezoelectric actuator, a polygonal scanner, a rotating-prism scanner, avoice coil motor, an electric motor (e.g., a DC motor, a brushless DCmotor, a synchronous electric motor, or a stepper motor), or amicroelectromechanical systems (MEMS) device, or any other suitableactuator or mechanism. In particular embodiments, scanner 120 may beconfigured to scan the output beam 125 over a 5-degree angular range,20-degree angular range, 30-degree angular range, 60-degree angularrange, or any other suitable angular range. As an example, a scanningmirror may be configured to periodically oscillate or rotate back andforth over a 15-degree range, which results in the output beam 125scanning across a 30-degree range (e.g., a Θ-degree rotation by ascanning mirror results in a 2Θ-degree angular scan of output beam 125).In particular embodiments, a field of regard (FOR) of a lidar system 100may refer to an area, region, or angular range over which the lidarsystem 100 may be configured to scan or capture distance information. Asan example, a lidar system 100 with an output beam 125 with a 30-degreescanning range may be referred to as having a 30-degree angular field ofregard. As another example, a lidar system 100 with a scanning mirrorthat rotates over a 30-degree range may produce an output beam 125 thatscans across a 60-degree range (e.g., a 60-degree FOR). In particularembodiments, lidar system 100 may have a FOR of approximately 10°, 20°,40°, 60°, 120°, or any other suitable FOR. In particular embodiments, aFOR may be referred to as a scan region.

In particular embodiments, scanner 120 may be configured to scan theoutput beam 125 (which includes at least a portion of the pulses oflight emitted by light source 110) across a FOR of the lidar system 100.In particular embodiments, scanner 120 may be configured to scan theoutput beam 125 horizontally and vertically, and lidar system 100 mayhave a particular FOR along the horizontal direction and anotherparticular FOR along the vertical direction. As an example, lidar system100 may have a horizontal FOR of 10° to 120° and a vertical FOR of 2° to45°. In particular embodiments, scanner 120 may include a first mirrorand a second mirror, where the first mirror directs the output beam 125toward the second mirror, and the second mirror directs the output beam125 downrange. As an example, the first mirror may scan the output beam125 along a first direction, and the second mirror may scan the outputbeam 125 along a second direction that is substantially orthogonal tothe first direction. As another example, the first mirror may scan theoutput beam 125 along a substantially horizontal direction, and thesecond mirror may scan the output beam 125 along a substantiallyvertical direction (or vice versa). In particular embodiments, scanner120 may be referred to as a beam scanner, optical scanner, or laserscanner.

In particular embodiments, one or more scanning mirrors may becommunicatively coupled to controller 150 which may control the scanningmirror(s) so as to guide the output beam 125 in a desired directiondownrange or along a desired scan pattern. In particular embodiments, ascan pattern (which may be referred to as an optical scan pattern,optical scan path, or scan path) may refer to a pattern or path alongwhich the output beam 125 is directed. As an example, scanner 120 mayinclude two scanning mirrors configured to scan the output beam 125across a 60° horizontal FOR and a 20° vertical FOR. The two scannermirrors may be controlled to follow a scan path that substantiallycovers the 60°×20° FOR. As an example, the scan path may result in apoint cloud with pixels that substantially cover the 60°×20° FOR. Thepixels may be approximately evenly distributed across the 60°×20° FOR.Alternately, the pixels may have a particular nonuniform distribution(e.g., the pixels may be distributed across all or a portion of the60°×20° FOR, and the pixels may have a higher density in one or moreparticular regions of the 60°×20° FOR).

In particular embodiments, a light source 110 may emit pulses of lightwhich are scanned by scanner 120 across a FOR of lidar system 100. Oneor more of the emitted pulses of light may be scattered by a target 130located downrange from the lidar system 100, and a receiver 140 maydetect at least a portion of the pulses of light scattered by the target130. In particular embodiments, receiver 140 may be referred to as aphotoreceiver, optical receiver, optical sensor, detector,photodetector, or optical detector. In particular embodiments, lidarsystem 100 may include a receiver 140 that receives or detects at leasta portion of input beam 135 and produces an electrical signal thatcorresponds to input beam 135. As an example, if input beam 135 includesan optical pulse, then receiver 140 may produce an electrical current orvoltage pulse that corresponds to the optical pulse detected by receiver140. As another example, receiver 140 may include one or more avalanchephotodiodes (APDs) or one or more single-photon avalanche diodes(SPADs). As another example, receiver 140 may include one or more PNphotodiodes (e.g., a photodiode structure formed by a p-typesemiconductor and a n-type semiconductor) or one or more PIN photodiodes(e.g., a photodiode structure formed by an undoped intrinsicsemiconductor region located between p-type and n-type regions).Receiver 140 may have an active region or an avalanche-multiplicationregion that includes silicon, germanium, or InGaAs. The active region ofreceiver 140 may have any suitable size, such as for example, a diameteror width of approximately 20-500 μm.

In particular embodiments, receiver 140 may include circuitry thatperforms signal amplification, sampling, filtering, signal conditioning,analog-to-digital conversion, time-to-digital conversion, pulsedetection, threshold detection, rising-edge detection, or falling-edgedetection. As an example, receiver 140 may include a transimpedanceamplifier that converts a received photocurrent (e.g., a currentproduced by an APD in response to a received optical signal) into avoltage signal. The voltage signal may be sent to pulse-detectioncircuitry that produces an analog or digital output signal 145 thatcorresponds to one or more characteristics (e.g., rising edge, fallingedge, amplitude, or duration) of a received optical pulse. As anexample, the pulse-detection circuitry may perform a time-to-digitalconversion to produce a digital output signal 145. The electrical outputsignal 145 may be sent to controller 150 for processing or analysis(e.g., to determine a time-of-flight value corresponding to a receivedoptical pulse).

In particular embodiments, controller 150 may be electrically coupled orcommunicatively coupled to light source 110, scanner 120, or receiver140. As an example, controller 150 may receive electrical trigger pulsesor edges from light source 110, where each pulse or edge corresponds tothe emission of an optical pulse by light source 110. As anotherexample, controller 150 may provide instructions, a control signal, or atrigger signal to light source 110 indicating when light source 110should produce optical pulses. Controller 150 may send an electricaltrigger signal that includes electrical pulses, where each electricalpulse results in the emission of an optical pulse by light source 110.In particular embodiments, the frequency, period, duration, pulseenergy, peak power, average power, or wavelength of the optical pulsesproduced by light source 110 may be adjusted based on instructions, acontrol signal, or trigger pulses provided by controller 150. Inparticular embodiments, controller 150 may be coupled to light source110 and receiver 140, and controller 150 may determine a time-of-flightvalue for an optical pulse based on timing information associated withwhen the pulse was emitted by light source 110 and when a portion of thepulse (e.g., input beam 135) was detected or received by receiver 140.In particular embodiments, controller 150 may include circuitry thatperforms signal amplification, sampling, filtering, signal conditioning,analog-to-digital conversion, time-to-digital conversion, pulsedetection, threshold detection, rising-edge detection, or falling-edgedetection.

In particular embodiments, a lidar system 100 may be used to determinethe distance to one or more downrange targets 130. By scanning the lidarsystem 100 across a field of regard, the system can be used to map thedistance to a number of points within the field of regard. Each of thesedepth-mapped points may be referred to as a pixel or a voxel. Acollection of pixels captured in succession (which may be referred to asa depth map, a point cloud, or a frame) may be rendered as an image ormay be analyzed to identify or detect objects or to determine a shape ordistance of objects within the FOR. As an example, a point cloud maycover a field of regard that extends 60° horizontally and 15°vertically, and the point cloud may include a frame of 100-2000 pixelsin the horizontal direction by 4-400 pixels in the vertical direction.

In particular embodiments, lidar system 100 may be configured torepeatedly capture or generate point clouds of a field of regard at anysuitable frame rate between approximately 0.1 frames per second (FPS)and approximately 1,000 FPS. As an example, lidar system 100 maygenerate point clouds at a frame rate of approximately 0.1 FPS, 0.5 FPS,1 FPS, 2 FPS, 5 FPS, 10 FPS, 20 FPS, 100 FPS, 500 FPS, or 1,000 FPS. Asanother example, lidar system 100 may be configured to produce opticalpulses at a rate of 5×10⁵ pulses/second (e.g., the system may determine500,000 pixel distances per second) and scan a frame of 1000×50 pixels(e.g., 50,000 pixels/frame), which corresponds to a point-cloud framerate of 10 frames per second (e.g., 10 point clouds per second). Inparticular embodiments, a point-cloud frame rate may be substantiallyfixed, or a point-cloud frame rate may be dynamically adjustable. As anexample, a lidar system 100 may capture one or more point clouds at aparticular frame rate (e.g., 1 Hz) and then switch to capture one ormore point clouds at a different frame rate (e.g., 10 Hz). A slowerframe rate (e.g., 1 Hz) may be used to capture one or morehigh-resolution point clouds, and a faster frame rate (e.g., 10 Hz) maybe used to rapidly capture multiple lower-resolution point clouds.

In particular embodiments, a lidar system 100 may be configured tosense, identify, or determine distances to one or more targets 130within a field of regard. As an example, a lidar system 100 maydetermine a distance to a target 130, where all or part of the target130 is contained within a field of regard of the lidar system 100. Allor part of a target 130 being contained within a FOR of the lidar system100 may refer to the FOR overlapping, encompassing, or enclosing atleast a portion of the target 130. In particular embodiments, target 130may include all or part of an object that is moving or stationaryrelative to lidar system 100. As an example, target 130 may include allor a portion of a person, vehicle, motorcycle, truck, train, bicycle,wheelchair, pedestrian, animal, road sign, traffic light, lane marking,road-surface marking, parking space, pylon, guard rail, traffic barrier,pothole, railroad crossing, obstacle in or near a road, curb, stoppedvehicle on or beside a road, utility pole, house, building, trash can,mailbox, tree, any other suitable object, or any suitable combination ofall or part of two or more objects.

In particular embodiments, one or more lidar systems 100 may beintegrated into a vehicle. As an example, multiple lidar systems 100 maybe integrated into a car to provide a complete 360-degree horizontal FORaround the car. As another example, 4-10 lidar systems 100, each systemhaving a 45-degree to 90-degree horizontal FOR, may be combined togetherto form a sensing system that provides a point cloud covering a360-degree horizontal FOR. The lidar systems 100 may be oriented so thatadjacent FORs have an amount of spatial or angular overlap to allow datafrom the multiple lidar systems 100 to be combined or stitched togetherto form a single or continuous 360-degree point cloud. As an example,the FOR of each lidar system 100 may have approximately 1-15 degrees ofoverlap with an adjacent FOR. In particular embodiments, a vehicle mayrefer to a mobile machine configured to transport people or cargo. Forexample, a vehicle may include, may take the form of, or may be referredto as a car, automobile, motor vehicle, truck, bus, van, trailer,off-road vehicle, farm vehicle, lawn mower, construction equipment,forklift, robot, golf cart, motorhome, taxi, motorcycle, scooter,bicycle, skateboard, train, snowmobile, watercraft (e.g., a ship orboat), aircraft (e.g., a fixed-wing aircraft, helicopter, or dirigible),unmanned aerial vehicle (e.g., drone), or spacecraft. In particularembodiments, a vehicle may include an internal combustion engine or anelectric motor that provides propulsion for the vehicle.

In particular embodiments, one or more lidar systems 100 may be includedin a vehicle as part of an advanced driver assistance system (ADAS) toassist a driver of the vehicle in the driving process. For example, alidar system 100 may be part of an ADAS that provides information orfeedback to a driver (e.g., to alert the driver to potential problems orhazards) or that automatically takes control of part of a vehicle (e.g.,a braking system or a steering system) to avoid collisions or accidents.A lidar system 100 may be part of a vehicle ADAS that provides adaptivecruise control, automated braking, automated parking, collisionavoidance, alerts the driver to hazards or other vehicles, maintains thevehicle in the correct lane, or provides a warning if an object oranother vehicle is in a blind spot.

In particular embodiments, one or more lidar systems 100 may beintegrated into a vehicle as part of an autonomous-vehicle drivingsystem. As an example, a lidar system 100 may provide information aboutthe surrounding environment to a driving system of an autonomousvehicle. An autonomous-vehicle driving system may include one or morecomputing systems that receive information from a lidar system 100 aboutthe surrounding environment, analyze the received information, andprovide control signals to the vehicle's driving systems (e.g., steeringwheel, accelerator, brake, or turn signal). As an example, a lidarsystem 100 integrated into an autonomous vehicle may provide anautonomous-vehicle driving system with a point cloud every 0.1 seconds(e.g., the point cloud has a 10 Hz update rate, representing 10 framesper second). The autonomous-vehicle driving system may analyze thereceived point clouds to sense or identify targets 130 and theirrespective locations, distances, or speeds, and the autonomous-vehicledriving system may update control signals based on this information. Asan example, if lidar system 100 detects a vehicle ahead that is slowingdown or stopping, the autonomous-vehicle driving system may sendinstructions to release the accelerator and apply the brakes.

In particular embodiments, an autonomous vehicle may be referred to asan autonomous car, driverless car, self-driving car, robotic car, orunmanned vehicle. In particular embodiments, an autonomous vehicle mayrefer to a vehicle configured to sense its environment and navigate ordrive with little or no human input. As an example, an autonomousvehicle may be configured to drive to any suitable location and controlor perform all safety-critical functions (e.g., driving, steering,braking, parking) for the entire trip, with the driver not expected tocontrol the vehicle at any time. As another example, an autonomousvehicle may allow a driver to safely turn their attention away fromdriving tasks in particular environments (e.g., on freeways), or anautonomous vehicle may provide control of a vehicle in all but a fewenvironments, requiring little or no input or attention from the driver.

In particular embodiments, an autonomous vehicle may be configured todrive with a driver present in the vehicle, or an autonomous vehicle maybe configured to operate the vehicle with no driver present. As anexample, an autonomous vehicle may include a driver's seat withassociated controls (e.g., steering wheel, accelerator pedal, and brakepedal), and the vehicle may be configured to drive with no one seated inthe driver's seat or with little or no input from a person seated in thedriver's seat. As another example, an autonomous vehicle may not includeany driver's seat or associated driver's controls, and the vehicle mayperform substantially all driving functions (e.g., driving, steering,braking, parking, and navigating) without human input. As anotherexample, an autonomous vehicle may be configured to operate without adriver (e.g., the vehicle may be configured to transport humanpassengers or cargo without a driver present in the vehicle). As anotherexample, an autonomous vehicle may be configured to operate without anyhuman passengers (e.g., the vehicle may be configured for transportationof cargo without having any human passengers onboard the vehicle).

Although this disclosure describes or illustrates example embodiments oflidar systems 100 or light sources 110 that produce light waveforms thatinclude pulses of light, the embodiments described or illustrated hereinmay also be applied to other types of light waveforms, includingcontinuous-wave (CW) light or modulated light waveforms. For example, alidar system 100 as described or illustrated herein may include a lightsource 110 configured to produce pulses of light. Alternatively, a lidarsystem 100 may be configured to act as a frequency-modulatedcontinuous-wave (FMCW) lidar system and may include a light source 110configured to produce CW light or a frequency-modulated light waveform.

A pulsed lidar system is one type of lidar system 100 in which the lightsource 110 emits pulses of light, and the distance to a remote target130 is determined from the time-of-flight for a pulse of light to travelto the target 130 and back. Another type of lidar system 100 is afrequency-modulated lidar system, which may be referred to as afrequency-modulated continuous-wave (FMCW) lidar system. A FMCW lidarsystem uses frequency-modulated light to determine the distance to aremote target 130 based on a modulation frequency of the received light(which is scattered from a remote target) relative to the modulationfrequency of the emitted light. For example, for a linearly chirpedlight source (e.g., a frequency modulation that produces a linear changein frequency with time), the larger the frequency difference between theemitted light and the received light, the farther away the target 130 islocated. The frequency difference can be determined by mixing thereceived light with a portion of the emitted light (e.g., by couplingthe two beams onto a detector, or mixing analog electric signalscorresponding to the received light and the emitted light) anddetermining the resulting beat frequency. For example, the electricalsignal from an APD can be analyzed using a fast Fourier transform (FFT)technique to determine the frequency difference between the emittedlight and the received light.

If a linear frequency modulation m (e.g., in units of Hz/s) is appliedto a CW laser, then the distance D from the target 130 to the lidarsystem 100 may be expressed as D=c·Δf/(2 m), where c is the speed oflight and Δf is the difference in frequency between the transmittedlight and the received light. For example, for a linear frequencymodulation of 10¹² Hz/s (or, 1 MHz/μs), if a frequency difference of 330kHz is measured, then the distance to the target is approximately 50meters. Additionally, a frequency difference of 1.33 MHz corresponds toa target located approximately 200 meters away.

The light source 110 for a FMCW lidar system can be a fiber laser (e.g.,a seed laser diode followed by one or more optical amplifiers) or adirect-emitter laser diode. The seed laser diode or the direct-emitterlaser diode can be operated in a CW manner (e.g., by driving the laserdiode with a substantially constant DC current), and the frequencymodulation can be provided by an external modulator (e.g., anelectro-optic phase modulator). Alternatively, the frequency modulationcan be produced by applying a DC bias current along with a currentmodulation to the seed laser diode or the direct-emitter laser diode.The current modulation produces a corresponding refractive-indexmodulation in the laser diode, which results in a frequency modulationof the light emitted by the laser diode. The current-modulationcomponent (and corresponding frequency modulation) can have any suitablefrequency or shape (e.g., piecewise linear, sinusoidal, triangle-wave,or sawtooth).

FIG. 2 illustrates an example scan pattern 200 produced by a lidarsystem 100. A scan pattern 200 (which may be referred to as a scan) mayrepresent a path or course followed by output beam 125 as it is scannedacross all or part of a FOR. Each traversal of a scan pattern 200 maycorrespond to the capture of a single frame or a single point cloud. Inparticular embodiments, a lidar system 100 may be configured to scanoutput optical beam 125 along one or more particular scan patterns 200.In particular embodiments, a scan pattern 200 may scan across anysuitable field of regard (FOR) having any suitable horizontal FOR(FOR_(H)) and any suitable vertical FOR (FOR_(V)). For example, a scanpattern 200 may have a field of regard represented by angular dimensions(e.g., FOR_(H)×FOR_(V)) 40°×30°, 90°×40°, or 60°×15°. As anotherexample, a scan pattern 200 may have a FOR_(H) greater than or equal to10°, 25°, 30°, 40°, 60°, 90°, or 120°. As another example, a scanpattern 200 may have a FOR_(V) greater than or equal to 2°, 5°, 10°,15°, 20°, 30°, or 45°.

In the example of FIG. 2, reference line 220 represents a center of thefield of regard of scan pattern 200. In particular embodiments,reference line 220 may have any suitable orientation, such as forexample, a horizontal angle of 0° (e.g., reference line 220 may beoriented straight ahead) and a vertical angle of 0° (e.g., referenceline 220 may have an inclination of 0°), or reference line 220 may havea nonzero horizontal angle or a nonzero inclination (e.g., a verticalangle of +10° or −10°). In FIG. 2, if the scan pattern 200 has a 60°×15°field of regard, then scan pattern 200 covers a ±30° horizontal rangewith respect to reference line 220 and a ±7.5° vertical range withrespect to reference line 220. Additionally, optical beam 125 in FIG. 2has an orientation of approximately −15° horizontal and +3° verticalwith respect to reference line 220. Optical beam 125 may be referred toas having an azimuth of −15° and an altitude of +3° relative toreference line 220. In particular embodiments, an azimuth (which may bereferred to as an azimuth angle) may represent a horizontal angle withrespect to reference line 220, and an altitude (which may be referred toas an altitude angle, elevation, or elevation angle) may represent avertical angle with respect to reference line 220.

In particular embodiments, a scan pattern 200 may include multiplepixels 210, and each pixel 210 may be associated with one or more laserpulses and one or more corresponding distance measurements. Inparticular embodiments, a cycle of scan pattern 200 may include a totalof P_(x)×P_(y) pixels 210 (e.g., a two-dimensional distribution of P_(x)by P_(y) pixels). As an example, scan pattern 200 may include adistribution with dimensions of approximately 100-2,000 pixels 210 alonga horizontal direction and approximately 4-400 pixels 210 along avertical direction. As another example, scan pattern 200 may include adistribution of 1,000 pixels 210 along the horizontal direction by 64pixels 210 along the vertical direction (e.g., the frame size is 1000×64pixels) for a total of 64,000 pixels per cycle of scan pattern 200. Inparticular embodiments, the number of pixels 210 along a horizontaldirection may be referred to as a horizontal resolution of scan pattern200, and the number of pixels 210 along a vertical direction may bereferred to as a vertical resolution. As an example, scan pattern 200may have a horizontal resolution of greater than or equal to 100 pixels210 and a vertical resolution of greater than or equal to 4 pixels 210.As another example, scan pattern 200 may have a horizontal resolution of100-2,000 pixels 210 and a vertical resolution of 4-400 pixels 210.

In particular embodiments, each pixel 210 may be associated with adistance (e.g., a distance to a portion of a target 130 from which anassociated laser pulse was scattered) or one or more angular values. Asan example, a pixel 210 may be associated with a distance value and twoangular values (e.g., an azimuth and altitude) that represent theangular location of the pixel 210 with respect to the lidar system 100.A distance to a portion of target 130 may be determined based at leastin part on a time-of-flight measurement for a corresponding pulse. Anangular value (e.g., an azimuth or altitude) may correspond to an angle(e.g., relative to reference line 220) of output beam 125 (e.g., when acorresponding pulse is emitted from lidar system 100) or an angle ofinput beam 135 (e.g., when an input signal is received by lidar system100). In particular embodiments, an angular value may be determinedbased at least in part on a position of a component of scanner 120. Asan example, an azimuth or altitude value associated with a pixel 210 maybe determined from an angular position of one or more correspondingscanning mirrors of scanner 120.

FIG. 3 illustrates an example lidar system 100 with an example overlapmirror 115. In particular embodiments, a lidar system 100 may include alight source 110 configured to emit pulses of light and a scanner 120configured to scan at least a portion of the emitted pulses of lightacross a field of regard. As an example, the light source 110 mayinclude a pulsed solid-state laser or a pulsed fiber laser, and theoptical pulses produced by the light source 110 may be directed throughaperture 310 of overlap mirror 115 and then coupled to scanner 120. Inparticular embodiments, a lidar system 100 may include a receiver 140configured to detect at least a portion of the scanned pulses of lightscattered by a target 130 located a distance D from the lidar system100. As an example, one or more pulses of light that are directeddownrange from lidar system 100 by scanner 120 (e.g., as part of outputbeam 125) may scatter off a target 130, and a portion of the scatteredlight may propagate back to the lidar system 100 (e.g., as part of inputbeam 135) and be detected by receiver 140.

In particular embodiments, lidar system 100 may include one or moreprocessors (e.g., a controller 150) configured to determine a distance Dfrom the lidar system 100 to a target 130 based at least in part on around-trip time of flight for an emitted pulse of light to travel fromthe lidar system 100 to the target 130 and back to the lidar system 100.The target 130 may be at least partially contained within a field ofregard of the lidar system 100 and located a distance D from the lidarsystem 100 that is less than or equal to a maximum range R_(MAX) of thelidar system 100. In particular embodiments, a maximum range (which maybe referred to as a maximum distance) of a lidar system 100 may refer tothe maximum distance over which the lidar system 100 is configured tosense or identify targets 130 that appear in a field of regard of thelidar system 100. The maximum range of lidar system 100 may be anysuitable distance, such as for example, 25 m, 50 m, 100 m, 200 m, 500 m,or 1 km. As an example, a lidar system 100 with a 200-m maximum rangemay be configured to sense or identify various targets 130 located up to200 m away from the lidar system 100. For a lidar system 100 with a200-m maximum range (R_(MAX)=200 m), the time of flight corresponding tothe maximum range is approximately 2·R_(MAX)/c≅1.33 μs.

In particular embodiments, light source 110, scanner 120, and receiver140 may be packaged together within a single housing, where a housingmay refer to a box, case, or enclosure that holds or contains all orpart of a lidar system 100. As an example, a lidar-system enclosure maycontain a light source 110, overlap mirror 115, scanner 120, andreceiver 140 of a lidar system 100. Additionally, the lidar-systemenclosure may include a controller 150. The lidar-system enclosure mayalso include one or more electrical connections for conveying electricalpower or electrical signals to or from the enclosure. In particularembodiments, one or more components of a lidar system 100 may be locatedremotely from a lidar-system enclosure. As an example, all or part oflight source 110 may be located remotely from a lidar-system enclosure,and pulses of light produced by the light source 110 may be conveyed tothe enclosure via optical fiber. As another example, all or part of acontroller 150 may be located remotely from a lidar-system enclosure.

In particular embodiments, light source 110 may include an eye-safelaser, or lidar system 100 may be classified as an eye-safe laser systemor laser product. An eye-safe laser, laser system, or laser product mayrefer to a system that includes a laser with an emission wavelength,average power, peak power, peak intensity, pulse energy, beam size, beamdivergence, exposure time, or scanned output beam such that emittedlight from the system presents little or no possibility of causingdamage to a person's eyes. As an example, light source 110 or lidarsystem 100 may be classified as a Class 1 laser product (as specified bythe 60825-1 standard of the International Electrotechnical Commission(IEC)) or a Class I laser product (as specified by Title 21, Section1040.10 of the United States Code of Federal Regulations (CFR)) that issafe under all conditions of normal use. In particular embodiments,lidar system 100 may be an eye-safe laser product (e.g., with a Class 1or Class I classification) configured to operate at any suitablewavelength between approximately 1400 nm and approximately 2100 nm. Asan example, lidar system 100 may include a laser with an operatingwavelength between approximately 1400 nm and approximately 1600 nm, andthe laser or the lidar system 100 may be operated in an eye-safe manner.As another example, lidar system 100 may be an eye-safe laser productthat includes a scanned laser with an operating wavelength betweenapproximately 1530 nm and approximately 1560 nm. As another example,lidar system 100 may be a Class 1 or Class I laser product that includesa fiber laser or solid-state laser with an operating wavelength betweenapproximately 1400 nm and approximately 1600 nm.

In particular embodiments, scanner 120 may include one or more mirrors,where each mirror is mechanically driven by a galvanometer scanner, aresonant scanner, a MEMS device, a voice coil motor, an electric motor,or any suitable combination thereof. A galvanometer scanner (which maybe referred to as a galvanometer actuator) may include agalvanometer-based scanning motor with a magnet and coil. When anelectrical current is supplied to the coil, a rotational force isapplied to the magnet, which causes a mirror attached to thegalvanometer scanner to rotate. The electrical current supplied to thecoil may be controlled to dynamically change the position of thegalvanometer mirror. A resonant scanner (which may be referred to as aresonant actuator) may include a spring-like mechanism driven by anactuator to produce a periodic oscillation at a substantially fixedfrequency (e.g., 1 kHz). A MEMS-based scanning device may include amirror with a diameter between approximately 1 and 10 mm, where themirror is rotated back and forth using electromagnetic or electrostaticactuation. A voice coil motor (which may be referred to as a voice coilactuator) may include a magnet and coil. When an electrical current issupplied to the coil, a translational force is applied to the magnet,which causes a mirror attached to the magnet to move or rotate. Anelectric motor, such as for example, a brushless DC motor or asynchronous electric motor, may be used to continuously rotate a mirrorat a substantially fixed frequency (e.g., a rotational frequency ofapproximately 1 Hz, 10 Hz, 50 Hz, 100 Hz, 500 Hz, or 1,000 Hz). Themirror may be continuously rotated in one rotation direction (e.g.,clockwise or counter-clockwise relative to a particular rotation axis).

In particular embodiments, a scanner 120 may include any suitable numberof mirrors driven by any suitable number of mechanical actuators. As anexample, a scanner 120 may include a single mirror configured to scan anoutput beam 125 along a single direction (e.g., a scanner 120 may be aone-dimensional scanner that scans along a horizontal or verticaldirection). The mirror may be driven by one actuator (e.g., agalvanometer) or two actuators configured to drive the mirror in apush-pull configuration. As another example, a scanner 120 may include asingle mirror that scans an output beam 125 along two directions (e.g.,horizontal and vertical). The mirror may be driven by two actuators,where each actuator provides rotational motion along a particulardirection or about a particular axis. As another example, a scanner 120may include two mirrors, where one mirror scans an output beam 125 alonga substantially horizontal direction and the other mirror scans theoutput beam 125 along a substantially vertical direction. In the exampleof FIG. 3, scanner 120 includes two mirrors, mirror 300-1 and mirror300-2. Mirror 300-2 rotates along the Θ_(y) direction and scans outputbeam 125 along a substantially vertical direction, and mirror 300-1rotates along the Θ_(x) direction and scans output beam 125 along asubstantially horizontal direction.

In particular embodiments, a scanner 120 may include two mirrors, whereeach mirror is driven by a corresponding galvanometer scanner. As anexample, scanner 120 may include a galvanometer actuator that scansmirror 300-1 along a first direction (e.g., horizontal), and scanner 120may include another galvanometer actuator that scans mirror 300-2 alonga second direction (e.g., vertical). In particular embodiments, ascanner 120 may include two mirrors, where one mirror is driven by agalvanometer actuator and the other mirror is driven by a resonantactuator. As an example, a galvanometer actuator may scan mirror 300-1along a first direction, and a resonant actuator may scan mirror 300-2along a second direction. The first and second scanning directions maybe substantially orthogonal to one another. As an example, the firstdirection may be substantially vertical, and the second direction may besubstantially horizontal, or vice versa. In particular embodiments, ascanner 120 may include two mirrors, where one mirror is driven by anelectric motor and the other mirror is driven by a galvanometeractuator. As an example, mirror 300-1 may be a polygon mirror that isrotated about a fixed axis by an electric motor (e.g., a brushless DCmotor), and mirror 300-2 may be driven by a galvanometer or MEMSactuator. In particular embodiments, a scanner 120 may include twomirrors, where both mirrors are driven by electric motors. As anexample, mirror 300-2 may be a polygon mirror driven by an electricmotor, and mirror 300-1 may be driven by another electric motor. Inparticular embodiments, a scanner 120 may include one mirror driven bytwo actuators which are configured to scan the mirror along twosubstantially orthogonal directions. As an example, one mirror may bedriven along a substantially horizontal direction by a resonant actuatoror a galvanometer actuator, and the mirror may also be driven along asubstantially vertical direction by a galvanometer actuator. As anotherexample, a mirror may be driven along two substantially orthogonaldirections by two resonant actuators or by two electric motors.

In particular embodiments, a scanner 120 may include a mirror configuredto be scanned along one direction by two actuators arranged in apush-pull configuration. Driving a mirror in a push-pull configurationmay refer to a mirror that is driven in one direction by two actuators.The two actuators may be located at opposite ends or sides of themirror, and the actuators may be driven in a cooperative manner so thatwhen one actuator pushes on the mirror, the other actuator pulls on themirror, and vice versa. As an example, a mirror may be driven along ahorizontal or vertical direction by two voice coil actuators arranged ina push-pull configuration. In particular embodiments, a scanner 120 mayinclude one mirror configured to be scanned along two axes, where motionalong each axis is provided by two actuators arranged in a push-pullconfiguration. As an example, a mirror may be driven along a horizontaldirection by two resonant actuators arranged in a horizontal push-pullconfiguration, and the mirror may be driven along a vertical directionby another two resonant actuators arranged in a vertical push-pullconfiguration.

In particular embodiments, a scanner 120 may include two mirrors whichare driven synchronously so that the output beam 125 is directed alongany suitable scan pattern 200. As an example, a galvanometer actuatormay drive mirror 300-1 with a substantially linear back-and-forth motion(e.g., the galvanometer may be driven with a substantially sinusoidal ortriangle-shaped waveform) that causes output beam 125 to trace asubstantially horizontal back-and-forth pattern. Additionally, anothergalvanometer actuator may scan mirror 300-2 along a substantiallyvertical direction. For example, the two galvanometers may besynchronized so that for every 64 horizontal traces, the output beam 125makes a single trace along a vertical direction. As another example, aresonant actuator may drive mirror 300-1 along a substantiallyhorizontal direction, and a galvanometer actuator or a resonant actuatormay scan mirror 300-2 along a substantially vertical direction.

In particular embodiments, a scanner 120 may include one mirror drivenby two or more actuators, where the actuators are driven synchronouslyso that the output beam 125 is directed along a particular scan pattern200. As an example, one mirror may be driven synchronously along twosubstantially orthogonal directions so that the output beam 125 followsa scan pattern 200 that includes substantially straight lines. Inparticular embodiments, a scanner 120 may include two mirrors drivensynchronously so that the synchronously driven mirrors trace out a scanpattern 200 that includes substantially straight lines. As an example,the scan pattern 200 may include a series of substantially straightlines directed substantially horizontally, vertically, or along anyother suitable direction. The straight lines may be achieved by applyinga dynamically adjusted deflection along a vertical direction (e.g., witha galvanometer actuator) as an output beam 125 is scanned along asubstantially horizontal direction (e.g., with a galvanometer orresonant actuator). If a vertical deflection is not applied, the outputbeam 125 may trace out a curved path as it scans from side to side. Byapplying a vertical deflection as the mirror is scanned horizontally, ascan pattern 200 that includes substantially straight lines may beachieved. In particular embodiments, a vertical actuator may be used toapply both a dynamically adjusted vertical deflection as the output beam125 is scanned horizontally as well as a discrete vertical offsetbetween each horizontal scan (e.g., to step the output beam 125 to asubsequent row of a scan pattern 200).

In the example of FIG. 3, lidar system 100 produces an output beam 125and receives light from an input beam 135. The output beam 125, whichincludes at least a portion of the pulses of light emitted by lightsource 110, may be scanned across a field of regard. The input beam 135may include at least a portion of the scanned pulses of light which arescattered by one or more targets 130 and detected by receiver 140. Inparticular embodiments, output beam 125 and input beam 135 may besubstantially coaxial. The input and output beams being substantiallycoaxial may refer to the beams being at least partially overlapped orsharing a common propagation axis so that input beam 135 and output beam125 travel along substantially the same optical path (albeit in oppositedirections). As output beam 125 is scanned across a field of regard, theinput beam 135 may follow along with the output beam 125 so that thecoaxial relationship between the two beams is maintained.

In particular embodiments, a lidar system 100 may include an overlapmirror 115 configured to overlap the input beam 135 and output beam 125so that they are substantially coaxial. In FIG. 3, the overlap mirror115 includes a hole, slot, or aperture 310 which the output beam 125passes through and a reflecting surface 320 that reflects at least aportion of the input beam 135 toward the receiver 140. The overlapmirror 115 may be oriented so that input beam 135 and output beam 125are at least partially overlapped. In particular embodiments, input beam135 may pass through a lens 330 which focuses the beam onto an activeregion of the receiver 140. The active region may refer to an area overwhich receiver 140 may receive or detect input light. The active regionmay have any suitable size or diameter d, such as for example, adiameter of approximately 25 μm, 50 μm, 80 μm, 100 μm, 200 μm, 500 μm, 1mm, 2 mm, or 5 mm. In particular embodiments, overlap mirror 115 mayhave a reflecting surface 320 that is substantially flat or thereflecting surface 320 may be curved (e.g., mirror 115 may be anoff-axis parabolic mirror configured to focus the input beam 135 onto anactive region of the receiver 140). A reflecting surface 320 (which maybe referred to as a reflective surface 320) may include a reflectivemetallic coating (e.g., gold, silver, or aluminum) or a reflectivedielectric coating, and the reflecting surface 320 may have any suitablereflectivity R at an operating wavelength of the light source 110 (e.g.,R greater than or equal to 70%, 80%, 90%, 95%, 98%, or 99%).

In particular embodiments, aperture 310 may have any suitable size ordiameter Φ₁, and input beam 135 may have any suitable size or diameterΦ₂, where Φ₂ is greater than Φ₁. As an example, aperture 310 may have adiameter Φ₁ of approximately 0.2 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 5 mm, or10 mm, and input beam 135 may have a diameter Φ₂ of approximately 2 mm,5 mm, 10 mm, 15 mm, 20 mm, 30 mm, 40 mm, or 50 mm. In particularembodiments, reflective surface 320 of overlap mirror 115 may reflectgreater than or equal to 70% of input beam 135 toward the receiver 140.As an example, if reflective surface 320 has a reflectivity R at anoperating wavelength of the light source 110, then the fraction of inputbeam 135 directed toward the receiver 140 may be expressed asR×[1−(Φ₁/Φ₂)²]. For example, if R is 95%, Φ₁ is 2 mm, and Φ₂ is 10 mm,then approximately 91% of input beam 135 may be directed toward thereceiver 140 by reflective surface 320.

FIG. 4 illustrates an example lidar system 100 with an example rotatingpolygon mirror 300-1. In particular embodiments, a scanner 120 mayinclude a polygon mirror 300-1 configured to scan output beam 125 alonga particular direction. In the example of FIG. 4, scanner 120 includestwo scanning mirrors: (1) a polygon mirror 300-1 that rotates along theΘ_(x) direction and (2) a scanning mirror 300-2 that oscillates back andforth along the Θ_(y) direction. The output beam 125 from light source110, which passes alongside mirror 115, is reflected by a reflectingsurface (e.g., surface 320A, 320B, 320C, or 320D) of polygon mirror300-1 and is then reflected by reflecting surface 320 of mirror 300-2.Scattered light from a target 130 returns to the lidar system 100 asinput beam 135. The input beam 135 reflects from mirror 300-2, polygonmirror 300-1, and mirror 115, which directs input beam 135 throughfocusing lens 330 and to receiver 140.

In particular embodiments, a polygon mirror 300-1 may be configured torotate along a Θ_(x) or Θ_(y) direction and scan output beam 125 along asubstantially horizontal or vertical direction, respectively. A rotationalong a Θ_(x) direction may refer to a rotational motion of mirror 300-1that results in output beam 125 scanning along a substantiallyhorizontal direction. Similarly, a rotation along a Θ_(y) direction mayrefer to a rotational motion that results in output beam 125 scanningalong a substantially vertical direction. In FIG. 4, mirror 300-1 is apolygon mirror that rotates along the Θ_(x) direction and scans outputbeam 125 along a substantially horizontal direction, and mirror 300-2rotates along the Θ_(y) direction and scans output beam 125 along asubstantially vertical direction. In particular embodiments, a polygonmirror 300-1 may be configured to scan output beam 125 along anysuitable direction. As an example, a polygon mirror 300-1 may scanoutput beam 125 at any suitable angle with respect to a horizontal orvertical direction, such as for example, at an angle of approximately0°, 10°, 20°, 30°, 45°, 60°, 70°, 80°, or 90° with respect to ahorizontal or vertical direction.

In particular embodiments, a polygon mirror 300-1 may refer to amulti-sided object having reflective surfaces 320 on two or more of itssides or faces. As an example, a polygon mirror may include any suitablenumber of reflective faces (e.g., 2, 3, 4, 5, 6, 7, 8, or 10 faces),where each face includes a reflective surface 320. A polygon mirror300-1 may have a cross-sectional shape of any suitable polygon, such asfor example, a triangle (with three reflecting surfaces 320), square(with four reflecting surfaces 320), pentagon (with five reflectingsurfaces 320), hexagon (with six reflecting surfaces 320), heptagon(with seven reflecting surfaces 320), or octagon (with eight reflectingsurfaces 320). In FIG. 4, the polygon mirror 300-1 has a substantiallysquare cross-sectional shape and four reflecting surfaces (320A, 320B,320C, and 320D). The polygon mirror 300-1 in FIG. 4 may be referred toas a square mirror, a cube mirror, or a four-sided polygon mirror. InFIG. 4, the polygon mirror 300-1 may have a shape similar to a cube,cuboid, or rectangular prism. Additionally, the polygon mirror 300-1 mayhave a total of six sides, where four of the sides are faces withreflective surfaces (320A, 320B, 320C, and 320D).

In particular embodiments, a polygon mirror 300-1 may be continuouslyrotated in a clockwise or counter-clockwise rotation direction about arotation axis of the polygon mirror 300-1. The rotation axis maycorrespond to a line that is perpendicular to the plane of rotation ofthe polygon mirror 300-1 and that passes through the center of mass ofthe polygon mirror 300-1. In FIG. 4, the polygon mirror 300-1 rotates inthe plane of the drawing, and the rotation axis of the polygon mirror300-1 is perpendicular to the plane of the drawing. An electric motormay be configured to rotate a polygon mirror 300-1 at a substantiallyfixed frequency (e.g., a rotational frequency of approximately 1 Hz (or1 revolution per second), 10 Hz, 50 Hz, 100 Hz, 500 Hz, or 1,000 Hz). Asan example, a polygon mirror 300-1 may be mechanically coupled to anelectric motor (e.g., a brushless DC motor or a synchronous electricmotor) which is configured to spin the polygon mirror 300-1 at arotational speed of approximately 160 Hz (or, 9600 revolutions perminute (RPM)).

In particular embodiments, output beam 125 may be reflected sequentiallyfrom the reflective surfaces (320A, 320B, 320C, and 320D) as the polygonmirror 300-1 is rotated. This results in the output beam 125 beingscanned along a particular scan axis (e.g., a horizontal or verticalscan axis) to produce a sequence of scan lines, where each scan linecorresponds to a reflection of the output beam 125 from one of thereflective surfaces of the polygon mirror 300-1. In FIG. 4, the outputbeam 125 reflects off of reflective surface 320A to produce one scanline. Then, as the polygon mirror 300-1 rotates, the output beam 125reflects off of reflective surfaces 320B, 320C, and 320D to produce asecond, third, and fourth respective scan line.

In particular embodiments, output beam 125 may be directed to pass by aside of mirror 115 rather than passing through mirror 115. As anexample, mirror 115 may not include an aperture 310, and the output beam125 may be directed to pass along a side of mirror 115. In the exampleof FIG. 3, lidar system includes an overlap mirror 115 with an aperture310 that output beam 125 passes through. In the example of FIG. 4,output beam 125 from light source 110 is directed to pass by mirror 115(which does not include an aperture 310) and then to polygon mirror300-1.

FIG. 5 illustrates an example light-source field of view (FOV_(L)) andreceiver field of view (FOV_(R)) for a lidar system 100. A light source110 of lidar system 100 may emit pulses of light as the FOV_(L) andFOV_(R) are scanned by scanner 120 across a field of regard (FOR). Inparticular embodiments, a light-source field of view may refer to anangular cone illuminated by the light source 110 at a particular instantof time. Similarly, a receiver field of view may refer to an angularcone over which the receiver 140 may receive or detect light at aparticular instant of time, and any light outside the receiver field ofview may not be received or detected. As an example, as the light-sourcefield of view is scanned across a field of regard, a portion of a pulseof light emitted by the light source 110 may be sent downrange fromlidar system 100, and the pulse of light may be sent in the directionthat the FOV_(L) is pointing at the time the pulse is emitted. The pulseof light may scatter off a target 130, and the receiver 140 may receiveand detect a portion of the scattered light that is directed along orcontained within the FOV_(R).

In particular embodiments, scanner 120 may be configured to scan both alight-source field of view and a receiver field of view across a fieldof regard of the lidar system 100. Multiple pulses of light may beemitted and detected as the scanner 120 scans the FOV_(L) and FOV_(R)across the field of regard of the lidar system 100 while tracing out ascan pattern 200. In particular embodiments, the light-source field ofview and the receiver field of view may be scanned synchronously withrespect to one another, so that as the FOV_(L) is scanned across a scanpattern 200, the FOV_(R) follows substantially the same path at the samescanning speed. Additionally, the FOV_(L) and FOV_(R) may maintain thesame relative position to one another as they are scanned across thefield of regard. As an example, the FOV_(L) may be substantiallyoverlapped with or centered inside the FOV_(R) (as illustrated in FIG.5), and this relative positioning between FOV_(L) and FOV_(R) may bemaintained throughout a scan. As another example, the FOV_(R) may lagbehind the FOV_(L) by a particular, fixed amount throughout a scan(e.g., the FOV_(R) may be offset from the FOV_(L) in a directionopposite the scan direction).

In particular embodiments, the FOV_(L) may have an angular size orextent Θ_(L) that is substantially the same as or that corresponds tothe divergence of the output beam 125, and the FOV_(R) may have anangular size or extent Θ_(R) that corresponds to an angle over which thereceiver 140 may receive and detect light. In particular embodiments,the receiver field of view may be any suitable size relative to thelight-source field of view. As an example, the receiver field of viewmay be smaller than, substantially the same size as, or larger than theangular extent of the light-source field of view. In particularembodiments, the light-source field of view may have an angular extentof less than or equal to 50 milliradians, and the receiver field of viewmay have an angular extent of less than or equal to 50 milliradians. TheFOV_(L) may have any suitable angular extent Θ_(L), such as for example,approximately 0.1 mrad, 0.2 mrad, 0.5 mrad, 1 mrad, 1.5 mrad, 2 mrad, 3mrad, 5 mrad, 10 mrad, 20 mrad, 40 mrad, or 50 mrad. Similarly, theFOV_(R) may have any suitable angular extent Θ_(R), such as for example,approximately 0.1 mrad, 0.2 mrad, 0.5 mrad, 1 mrad, 1.5 mrad, 2 mrad, 3mrad, 5 mrad, 10 mrad, 20 mrad, 40 mrad, or 50 mrad. In particularembodiments, the light-source field of view and the receiver field ofview may have approximately equal angular extents. As an example, Θ_(L)and Θ_(R) may both be approximately equal to 1 mrad, 2 mrad, or 4 mrad.In particular embodiments, the receiver field of view may be larger thanthe light-source field of view, or the light-source field of view may belarger than the receiver field of view. As an example, Θ_(L) may beapproximately equal to 3 mrad, and Θ_(R) may be approximately equal to 4mrad.

In particular embodiments, a pixel 210 may represent or may correspondto a light-source field of view or a receiver field of view. As theoutput beam 125 propagates from the light source 110, the diameter ofthe output beam 125 (as well as the size of the corresponding pixel 210)may increase according to the beam divergence Θ_(L). As an example, ifthe output beam 125 has a Θ_(L) of 2 mrad, then at a distance of 100 mfrom the lidar system 100, the output beam 125 may have a size ordiameter of approximately 20 cm, and a corresponding pixel 210 may alsohave a corresponding size or diameter of approximately 20 cm. At adistance of 200 m from the lidar system 100, the output beam 125 and thecorresponding pixel 210 may each have a diameter of approximately 40 cm.

FIG. 6 illustrates an example scan pattern 200 that includes multiplescan lines 410 and multiple pixels 210. In particular embodiments, scanpattern 200 may include any suitable number of scan lines 410 (e.g.,approximately 1, 2, 5, 10, 20, 50, 100, 500, or 1,000 scan lines 410),and each scan line 410 of a scan pattern 200 may include any suitablenumber of pixels (e.g., 1, 2, 5, 10, 20, 50, 100, 200, 500, 1,000,2,000, or 5,000 pixels 210). The scan pattern 200 illustrated in FIG. 6includes approximately nine scan lines 410, and each scan line 410includes approximately 18 pixels 210. In particular embodiments, eachscan line 410 of a scan pattern 200 may include approximately the samenumber of pixels 210. As an example, each scan line 410 of a scanpattern 200 may include between approximately 950 and approximately1,050 pixels 210. In particular embodiments, a scan pattern 200 wherethe scan lines 410 are scanned in two directions may be referred to as abidirectional scan pattern 200, and a scan pattern 200 where the scanlines 410 are scanned in the same direction may be referred to as aunidirectional scan pattern 200. The scan pattern 200 in FIG. 6 may bereferred to as a bidirectional scan pattern 200 where the scan lines 410alternate between scanning from right to left and scanning from left toright. A bidirectional scan pattern 200 may be produced by a scanner 120that includes a scanning mirror that oscillates in a back-and-forthmotion corresponding to the bidirectional scan pattern 200.

In particular embodiments, a scan pattern 200 may include a retrace 400where a scanner 120 resets from an end point of a scan 200 back to astarting point of the scan 200. The scan pattern 200 illustrated in FIG.6 starts at the upper-left portion of the FOR and ends at thelower-right portion. In FIG. 6, the scan pattern 200 includes retrace400 represented by a dashed diagonal line that connects the end of scanpattern 200 to the beginning. In particular embodiments, lidar system100 may not send out pulses or acquire distance data during a retrace400, or lidar system 100 may acquire distance data during a retrace 400(e.g., a retrace path may include one or more pixels 210).

In particular embodiments, the pixels 210 of a scan pattern 200 may besubstantially evenly spaced with respect to time or angle. As anexample, each pixel 210 (and its associated pulse) may be separated froman immediately preceding or following pixel 210 by any suitable timeinterval, such as for example a time interval of approximately 0.5 μs,1.0 μs, 1.4 μs, or 2.0 μs. In FIG. 6, pixels 210A, 210B, and 210C may beassociated with pulses that were emitted with a 1.6 μs fixed timeinterval between the pulses. As another example, each pixel 210 (and itsassociated pulse) may be separated from an immediately preceding orfollowing pixel 210 by any suitable angle, such as for example an angleof approximately 0.01°, 0.02°, 0.05°, 0.1°, 0.2°, 0.3°, 0.5°, or 1°. InFIG. 6, pixels 210A and 210B may have an angular separation ofapproximately 0.1° (e.g., pixels 210A and 210B may each be associatedwith optical beams separated by an angle of 0.1°). In particularembodiments, the pixels 210 of a scan pattern 200 may have an adjustablespacing with respect to time or angle. As an example, a time interval orangle separating two successive pixels 210 may be dynamically variedduring a scan or from one scan to a subsequent scan.

In particular embodiments, lidar system 100 may include a scanner 120configured to direct output beam 125 along any suitable scan pattern200. As an example, all or part of scan pattern 200 may follow asubstantially sinusoidal path, triangle-wave path, square-wave path,sawtooth path, piecewise linear path, periodic-function path, or anyother suitable path or combination of paths. In the example of FIG. 6,scan pattern 200 corresponds to an approximately sinusoidal path, wherepixels 210 are arranged along a sinusoidal curve.

In particular embodiments, pixels 210 may be substantially evenlydistributed across scan pattern 200, or pixels 210 may have adistribution or density that varies across a FOR of scan pattern 200. Inthe example of FIG. 6, pixels 210 have a greater density toward the leftand right edges of the FOR, and the pixel density in the middle regionof the FOR is lower compared to the edges. As an example, pixels 210 maybe distributed so that ≤40% of the pixels 210 are located in the left25% of the FOR, ≥40% of the pixels 210 are located in the right 25% ofthe FOR, and the remaining <20% of the pixels 210 are located in themiddle 50% of the FOR. In particular embodiments, a time interval orangle between pixels 210 may be dynamically adjusted during a scan sothat a scan pattern 200 has a particular distribution of pixels 210(e.g., a higher density of pixels 210 in one or more particularregions). As an example, a scan pattern 200 may be configured to have ahigher density of pixels 210 in a middle or central region of scan 200or toward one or more edges of scan 200 (e.g., a middle region or aleft, right, upper, or lower edge that includes approximately 5%, 10%,20%, 30%, or any other suitable percentage of the FOR of scan pattern200). For example, pixels 210 may be distributed so that ≥50% of thepixels 210 are located in a central, left, or right region of scanpattern 200 with the remaining <50% of the pixels 210 distributedthroughout the rest of scan pattern 200. As another example, a scanpattern 200 may have a higher density of pixels along a right edge ofthe scan pattern 200 than along a left edge of the scan pattern 200.

In particular embodiments, a distribution of pixels 210 in a scanpattern 200 may be determined, at least in part, by a pulse period oflight source 110, a scanning speed provided by scanner 120, or a shapeor path followed by scan pattern 200. As an example, the pulse period oflight source 110 may be a substantially fixed value, or the pulse periodmay be adjusted dynamically during a scan to vary the density of pixels210 across the scan region. As another example, an angular speed withwhich a mirror (e.g., mirror 300-1 or mirror 300-2) of scanner 120rotates may be substantially fixed or may vary during a scan. As anotherexample, a scan pattern 200 may provide for a varying distribution ofpixels 210 based on a shape of the pattern. For example, a triangle-wavescan pattern 200 (combined with a substantially constant pulse periodand angular speed) may provide a substantially uniform distribution ofpixels 210 along the horizontal direction, while a sinusoidal scanpattern 200 may result in a higher density of pixels 210 along the leftand right edges and a lower density of pixels 210 in the middle region.Additionally, two or more scan parameters may be selected or adjusted tooptimize or adjust the density of pixels 210 in a scan pattern 200. Asan example, a sinusoidal scan pattern 200 may be combined with adynamically adjusted pulse period of light source 100 to provide for ahigher density of pixels 210 along the right edge and a lower density ofpixels 210 in the middle region and along the left edge.

In particular embodiments, a particular scan pattern 200 may be repeatedfrom one scan to the next, or one or more parameters of a scan pattern200 may be adjusted or varied within a scan or from one scan to another.As an example, a time interval or angle between pixels 210 may be variedfrom one scan to another scan. A relatively long time interval may beapplied in an initial scan to produce a moderate-density point cloud,and a relatively short time interval may be applied in a subsequent scanto produce a high-density point cloud. As another example, a timeinterval or angle between pixels 210 may be varied within a particularscan pattern 200. For a particular region of a scan pattern 200, a timeinterval may be decreased to produce a higher density of pixels 210within that particular region.

FIG. 7 illustrates an example scan pattern 200 with a substantiallyuniform distribution of scan lines 410. Scan pattern 200 illustrated inFIG. 7 is a bidirectional scan pattern 200 where scan line 410 travelsacross the FOR from left to right, and scan line 410′ travels from rightto left (or vice versa). In particular embodiments, a bidirectional scanpattern 200 may include multiple reversal regions 420 where the scanpattern 200 switches from scanning in one direction to scanning inanother direction. Each adjacent pair of scan lines 410 of abidirectional scan pattern 200 may be coupled together by a reversalregion 420. In FIG. 7, reversal region 420 may correspond to atransition from the left-to-right scan of scan line 410 to theright-to-left scan of scan line 410′. In particular embodiments, abidirectional scan pattern 200 may be produced by a scanner 120 thatincludes a scanning mirror configured to be driven repeatedly in aback-and-forth motion by any suitable mechanical actuator, such as forexample, a galvanometer scanner, a resonant scanner, or a MEMS-basedscanner. Additionally, each scan line 410 of a bidirectional scanpattern 200 may correspond to a single forward or backward motion of agalvanometer scanner. As an example, mirror 300-1 in FIG. 3 may producea back-and-forth oscillatory motion that results in a correspondingback-and-forth motion of the output beam 125. Scan line 410 in FIG. 7may be produced by a forward motion of mirror 300-1 in FIG. 3, and scanline 410′ may be produced by a backward motion of mirror 300-1.

In the example of FIG. 7, point 430A may correspond to a starting pointof the scan 200, and point 430B may correspond to an end point of thescan 200, or vice versa. As an example, the scan pattern 200 may startat point 430A and scan across the FOR in a top-to-bottom manner untilreaching the end point 430B. As another example, the scan pattern 200may start at point 430B and scan across the FOR in a bottom-to-topmanner until reaching the end point 430A. In FIG. 7, a retrace path 400is not included for clarity of illustrating the details of the scanpattern 200. Similarly, scan patterns 200 illustrated in other figuresdescribed herein may not include a retrace path 400, even though inpractice the scan pattern 200 may operate with a retrace path 400 thatconnects the end of the scan pattern 200 to the start. In the example ofFIG. 7, pixels 210 are not included in the scan pattern 200 for clarityof illustrating the scan pattern 200. Similarly, scan patterns 200illustrated in other figures described herein may not include pixels 210for clarity of illustrating the scan pattern 200, even though inpractice the scan pattern 200 may include multiple pixels 210.

In particular embodiments, a scan pattern 200 may include a scan-patternx-component and a scan-pattern y-component. The x-component maycorrespond to a horizontal angular scan, and they-component maycorrespond to a vertical angular scan, or vice versa. As an example,polygon mirror 300-1 in FIG. 4 may provide the x-component of a scanpattern 200, and mirror 300-2 may provide the y-component of the scanpattern 200. The x-component and y-component together may represent theshape, location, or angular distribution of scan lines 410 across a FOR.In particular embodiments, a horizontal angular scan may be referred toas an azimuthal scan, and a vertical angular scan may be referred to asan elevation scan or an altitude scan. In particular embodiments, axesΘ_(x) and Θ_(y) may be referred to as scan axes of scan pattern 200, andthe shape, location, or angular distribution of scan lines 410 across aFOR may be provided with respect to the scan axes Θ_(x) and Θ_(y). Thescan-pattern x-component may correspond to motion with respect to scanaxis Θ_(x), and the scan-pattern y-component may correspond to motionwith respect to scan axis Θ_(y). As an example, scan axis Θ_(x) maycorrespond to a direction or orientation of the scan lines 410, whereeach scan line 410 is directed or oriented substantially parallel toscan axis Θ_(x). Additionally, the distribution of scan lines 410 withina FOR may be represented with respect to scan axis Θ_(y). In FIG. 7, thescan lines 410 of scan pattern 200 are oriented substantially parallelto scan axis Θ_(x), and the scan lines 410 are distributed substantiallyuniformly along scan axis Θ_(y). Scan axis Θ_(x) in FIG. 7 maycorrespond to FOR_(H) and may extend horizontally from −30 degrees to+30 degrees. Similarly, scan axis Θ_(y) may correspond to FOR_(V) andmay extend vertically from −10 degrees to +10 degrees.

In particular embodiments, the angles Θ_(min) and Θ_(max) may representthe minimum and maximum angles, respectively, of a scan pattern 200 or aFOR along the scan axis Θ_(y). The angular size of the FOR_(V) may haveany suitable angular value, and the angles Θ_(min) and Θ_(max) may haveany suitable angular values. As an example, the angular range or extentof FOR_(V) may be approximately 30°, and the angles Θ_(min) and Θ_(max)may be approximately −15° and +15°, respectively. As another example,FOR_(V) may be approximately 30°, and the angles Θ_(min) and Θ_(max) maybe approximately −10° and +20°, respectively.

In particular embodiments, a scan pattern 200 may include scan lines 410having any suitable alignment or orientation, such as for example,horizontal, vertical, or oriented at approximately 10, 30, 45, or 60degrees with respect to a horizontal or vertical direction. Similarly,the scan axes Θ_(x) and Θ_(y) may have any suitable alignment ororientation. As an example, scan axis Θ_(x) may have a substantiallyhorizontal orientation, and scan axis Θ_(y) may have a substantiallyvertical orientation, or vice versa. In FIG. 7, scan axis Θ_(x) has asubstantially horizontal orientation, and scan axis Θ_(y) has asubstantially vertical orientation. In particular embodiments, scan axisΘ_(x) and scan axis Θ_(y) may be substantially orthogonal to oneanother. As an example, scan axis Θ_(x) may be oriented to withinapproximately 10° of a horizontal direction, and scan axis Θ_(y) may beoriented to within approximately 10° of a vertical direction. Inparticular embodiments, the scan axes Θ_(x) and Θ_(y) beingsubstantially orthogonal to one another may refer to scan axis Θ_(x) andscan axis Θ_(y) being orthogonal to within any suitable angular amount,such as for example, to within 0.1°, 0.5°, 1°, 5°, 10°, or 20°. Forexample, scan axis Θ_(y) may be oriented at an angle of approximately85° with respect to scan axis Θ_(x). As another example, scan axis Θ_(y)may be oriented at 90°±2° with respect to scan axis Θ_(x).

In particular embodiments, the scan lines 410 of a scan pattern 200 maybe distributed, positioned, or arranged within the range of FOR_(V) andalong scan axis Θ_(y) in any suitable manner. In FIG. 7, the scan lines410 are arranged between Θ_(min) and Θ_(max), the minimum and maximumangles, respectively, of FOR_(V). In FIG. 7, the scan lines 410 arearranged in a substantially uniform manner along scan axis Θ_(y), whereadjacent scan lines 410 are separated by a substantially fixedseparation distance or angle. As an example, the vertical FOR in FIG. 7may be approximately 16°, and adjacent scan lines 410 may have asubstantially constant angular separation of approximately 1°. Asanother example, for a scan pattern 200 with 60 scan lines 410 uniformlydistributed within a FOR_(V) of 30°, adjacent scan lines 410 may beseparated by approximately 0.5°. As another example, for a scan pattern200 with 400 scan lines 410 uniformly distributed within a FOR_(V) of20°, adjacent scan lines 410 may be separated by approximately 0.05°.

FIG. 8 illustrates an example scan pattern 200 with a nonuniformdistribution of scan lines 410. In particular embodiments, scanner 120may be configured to distribute scan lines 410 along scan axis Θ_(y) ina nonuniform manner to provide a scan pattern 200 with an adjustabledensity of scan lines 410. The adjustable-density scan pattern 200illustrated in FIG. 8 includes a higher density of scan lines 410between angles Θ₁ and Θ₂ and a lower density of scan lines 410 betweenangles Θ_(min) and Θ₁ and between angles Θ₂ and Θ_(max). In particularembodiments, a scan pattern 200 with a nonuniform distribution of scanlines 410 may include two or more regions having two or more respectivescan-line densities. As an example, a scan pattern 200 may include oneregion with a lower density of scan lines 410 and another region with ahigher density of scan lines 410. In the example of FIG. 8, thebidirectional, adjustable-density scan pattern 200 includes two regionswith a lower density of scan lines 410 (the regions between anglesΘ_(min) and Θ₁ and between angles Θ₂ and Θ_(max)) and one region with ahigher density of scan lines 410 (the region between angles Θ₁ and Θ₂).

In particular embodiments, a nonuniform distribution of scan lines 410may be provided by a scanner 120 that includes a scanning mirror with anadjustable scan rate. As an example, scanner 120 in FIG. 4 may producean adjustable-density scan pattern 200 based on scanning mirror 300-2having an adjustable scan rate along the Θ_(y) scan axis. Mirror 300-2may have a relatively high scan rate when scanning between anglesΘ_(min) and Θ₁ and between angles Θ₂ and Θ_(max), which results in arelatively low density of scan lines 410 in those regions. When scanningbetween angles Θ₁ and Θ₂, mirror 300-2 may be adjusted to have arelatively low scan rate, which results in a relatively high density ofscan lines 410. In particular embodiments, the region of higher-densityscan lines 410 between angles Θ₁ and Θ₂ may be located or adjusted inany suitable manner. As an example, the values of Θ₁ and Θ₂ may beapproximately −2° and +2°, respectively, or approximately −5° and +3°,respectively. Additionally, the values of Θ₁ or Θ₂ may be updated fromone scan to another. As another example, the value of Θ₂-Θ₁ (whichrepresents an angular range of the higher-density scan region) may beapproximately 0.5°, 1°, 2°, 5°, 10°, or 20°, and the value of Θ₂-Θ₁ maybe updated from one scan to another.

FIG. 9 illustrates an example focused scan pattern 200. In particularembodiments, a focused scan pattern 200 may be referred to as a focusedscan, a targeted scan pattern, or a targeted scan. In the example ofFIG. 9, the full FOR_(V) along the Θ_(y) scan axis extends from Θ_(min)to Θ_(max), and the focused scan pattern 200 is located within theFOR_(V) and between the angles Θ′_(min) and Θ′_(max). In particularembodiments, the location or angular range of a focused scan pattern 200may be adjusted in any suitable manner. As an example, the valuesΘ′_(min) and Θ′_(max) may be approximately −4° and +4°, respectively, orapproximately 0° and +3°, respectively. As another example, the value ofΘ′_(max)-Θ′_(min) (which represents an angular range or extent of thefocused scan pattern 200) may be approximately 0.5°, 1°, 2°, 5°, 10°, or20°. In particular embodiments, a focused scan pattern 200 may include arelatively high density of scan lines 410 located within a portion of aFOR_(V). In particular embodiments, a lidar system 100 may perform ascan that covers a full FOR (e.g., a uniform scan as illustrated in FIG.7), and then the lidar system 100 may perform a targeted scan thatcovers a portion of the FOR. A targeted scan may provide a higherdensity of scan lines 410 or pixels 210 and may reveal additionalinformation about a target 130 that is at least partially containedwithin the region of the targeted scan.

In particular embodiments, a focused scan pattern 200 may be provided bya scanner 120 that includes a scanning mirror (e.g., scanning mirror300-2 in FIG. 4) configured to adjust the angles of the scan pattern 200along the Θ_(y) scan axis. As an example, scanning mirror 300-2 in FIG.4 may be configured to scan an output beam 125 over the full FOR_(V)along the Θ_(y) scan axis between the angles Θ_(min) and Θ_(max).Additionally, the scan angles of scanning mirror 300-2 in FIG. 4 may beadjusted to scan between the angles Θ′_(min) and Θ′_(max) to produce afocused scan pattern 200.

In particular embodiments, scan lines 410 may be distributed along theΘ_(y) scan axis with any suitable scan-line density or with any suitablecombination of scan-line densities. As an example, scan lines 410 mayhave a scan-line density along the Θ_(y) scan axis of approximately 0.1,0.2, 0.5, 1, 2, 5, 10, 20, or 50 scan lines per degree. In the exampleof FIG. 7, the vertical FOR may be approximately 16°, and the scan lines410 may have a substantially constant scan-line density of approximately1 scan line per degree. As another example, for a scan pattern 200 with64 scan lines 410 uniformly distributed within a FOR_(V) of 20°, thescan lines 410 may have a scan-line density of approximately 3.2 scanlines per degree. In the example of FIG. 8, the scan-line density mayvary between approximately 2 scan lines per degree (for angles Θ_(min)to Θ₁ and angles Θ₂ to Θ_(max)) and approximately 8 scan lines perdegree (for angles Θ₁ to Θ₂). In the example of FIG. 9, for the focusedscan pattern 200 located between angles Θ′_(min) and Θ′_(max), thescan-line density may be approximately 5, 10, or 20 scan lines perdegree.

FIG. 10 illustrates an example scan pattern 200 with a substantiallyuniform distribution of scan lines 410. Scan pattern 200 illustrated inFIG. 10 is a unidirectional scan pattern 200 where each scan line 410travels across the FOR in substantially the same direction (e.g., fromleft to right). In particular embodiments, scan lines 410 of aunidirectional scan pattern 200 may be directed across a FOR in anysuitable direction, such as for example, from left to right, from rightto left, from top to bottom, from bottom to top, or at any suitableangle (e.g., at a 5°, 10°, 30°, or 45° angle) with respect to ahorizontal or vertical axis. In particular embodiments, a unidirectionalscan pattern 200 may not include a reversal region 420, and each scanline 410 may be a separate line that is not directly connected to aprevious or subsequent scan line 410.

In particular embodiments, a unidirectional scan pattern 200 may beproduced by a scanner 120 that includes a polygon mirror (e.g., polygonmirror 300-1 of FIG. 4), where each scan line 410 is associated with aparticular reflective surface 320 of the polygon mirror. As an example,reflective surface 320A of polygon mirror 300-1 in FIG. 4 may producescan line 410A in FIG. 10. Similarly, as the polygon mirror 300-1rotates, reflective surfaces 320B, 320C, and 320D may successivelyproduce scan lines 410B, 410C, and 410D, respectively. Additionally, fora subsequent revolution of the polygon mirror 300-1, the scan lines410A′, 410B′, 410C′, and 410D′ may be successively produced byreflections of the output beam 125 from reflective surfaces 320A, 320B,320C, and 320D, respectively. In particular embodiments, N successivescan lines 410 of a unidirectional scan pattern 200 may correspond toone full revolution of a N-sided polygon mirror. As an example, the fourscan lines 410A, 410B, 410C, and 410D in FIG. 10 may correspond to onefull revolution of the four-sided polygon mirror 300-1 in FIG. 4.Additionally, a subsequent revolution of the polygon mirror 300-1 mayproduce the next four scan lines 410A′, 410B′, 410C′, and 410D′ in FIG.10.

In particular embodiments, during at least a portion of a scan, lightsource 110 may be configured to emit pulses of light at a substantiallyconstant pulse repetition frequency, or light source 110 may beconfigured to vary the pulse repetition frequency. Additionally, ascanning mirror of scanner 120 may scan output beam 125 (which includesat least a portion of the pulses of light emitted by the light source110) at a substantially constant angular scanning speed. As an example,polygon mirror 300-1 in FIG. 4 may rotate at a substantially constantrotation speed, and the output beam 125 may scan across the FOR (e.g.,along scan axis Θ_(x)) at a corresponding constant angular scanningspeed. If a polygon mirror 300-1 has a rotation speed of R (e.g., inunits of revolutions per second or degrees per second), then the outputbeam 125 may scan across the FOR at an angular scanning speed ofapproximately 2R, since a Θ-degree rotation of polygon mirror 300-1results in a 2Θ-degree angular motion of output beam 125. For example,if the polygon mirror 300-1 has a rotation speed of 10,000 degrees persecond, then the output beam 125 may scan across the FOR at an angularscanning speed of approximately 20,000 degrees per second. In particularembodiments, the number of scan lines 410 per second produced by apolygon mirror 300-1 with N reflective surfaces 320 and a rotation speedR may be expressed as R×N, where R has units of revolutions per second.As an example, if the 4-sided polygon mirror 300-1 in FIG. 4 has arotation speed of 150 revolutions per second, then the lidar system 100may produce approximately 600 scan lines 410 per second.

In particular embodiments, the angular scanning speed ω_(x) (in units ofdeg/s) of the output beam 125 along scan axis Θ_(x) may be expressed asω_(x)=2×R×360, where R has units of revolutions per second. For example,if polygon mirror 300-1 rotates at 100 revolutions per second (whichcorresponds to an angular rotation rate of approximately 36,000 degreesper second, or 628 radians per second), then the output beam 125 mayscan along scan axis Θ_(x) at an angular scanning speed of approximately72,000 degrees per second (or approximately 1,257 radians per second).The expression FOR_(H)/(2×R×360) represents the time for the output beam125 to make a single scan across FOR_(H) (along scan axis Θ_(x)) andproduce a single scan line 410. As an example, for a FOR_(H) of 60° anda 100-Hz rotation speed (100 revolutions per second), one scan line 410may be traced across the FOR_(H) in approximately 0.83 ms. In particularembodiments, each scan line 410 of a scan pattern 200 may includeapproximately the same number of pixels 210. As an example, if thelight-source pulse repetition frequency (PRF) is substantially constantand the rotation speed R of polygon mirror 300-1 is substantiallyconstant, then each scan line 410 may include approximately the samenumber of pixels 210. As another example, each of the scan lines 410 inFIG. 10 may include approximately 1,000 pixels 210. The approximatenumber of pixels 210 in one scan line 410 may be found from theexpression P=(PRF×FOR_(H))/(2×R×360). For example, if the rotation speedR is 100 revolutions per second, the FOR_(H) is 60° degrees, and the PRFis 600 kHz, then each scan line 410 includes approximately P=500 pixels210.

In particular embodiments, the output beam 125 may have any suitableangular scan rate along the Θ_(y) scan axis, such as for example anangular scan rate of approximately 1, 2, 5, 10, 20, 50, 100, 300, or1,000 degrees per second. In particular embodiments, an angular scanrate may be referred to as a scan rate, a scan speed, an angular scanspeed, a scanning speed, or an angular scanning speed. The angularscanning speed along scan axis Θ_(y) may be expressed asω_(y)=ΔΘ_(y)/τ_(y), where ΔΘ_(y) is an angular range of the scan pattern200 along the Θ_(y) scan axis, and τ_(y) is a time for the output beam125 to travel across ΔΘ_(y) and trace out a single scan pattern 200 froma starting point to an end point (not including the time to perform aretrace 400). As an example, if ΔΘ_(y) is 30° and τ_(y) is 100 ms, thenthe angular scanning speed along scan axis Θ_(y) is approximately 300degrees per second. As another example, if ΔΘ_(y) is 2° and τ_(y) is 40ms, then the angular scanning speed along scan axis Θ_(y) isapproximately 50 degrees per second. In FIG. 10, the angular scan rangealong the Θ_(y) scan axis is approximately equal to FOR_(V). The scantime τ_(y) may be related to the frame rate F at which the lidar system100 scans by the expression F=1/(τ_(y)+τ_(retrace)), where τ_(retrace)is a time for the output beam 125 to traverse the retrace path 400.Based on this, the angular scanning speed along scan axis Θ_(y) may beexpressed as ω_(y)=(ΔΘ_(y)×F)/(1−F×τ_(retrace)). As an example, for a10-Hz frame rate over a 30° range with a 10 ms retrace time, thescanning speed ω_(y) is approximately 333 degrees per second. As anotherexample, for a 1-Hz scan rate over a 5° range with a 20 ms retrace time,the scanning speed ω_(y) is approximately 5.1 degrees per second.

In particular embodiments, a scan line 410 may have an incline angle δwith respect to the Θ_(x) axis. The incline angle δ may have anysuitable value, such as for example, approximately 0°, 0.1°, 0.2°, 0.5°,1°, 2°, 5°, or 10°. The incline angle δ may be oriented upward ordownward according to the direction the output beam 125 is scanned alongthe Θ_(y) scan axis. In FIG. 10, the output beam is scanned along theΘ_(y) scan axis from top to bottom, and each scan line 410 is angleddownward (with respect to the Θ_(x) axis) at an incline angle δ ofapproximately 4°. In particular embodiments, the incline angle δ maydepend on the angular scanning speeds along the scan axes Θ_(x) andΘ_(y) and may be expressed as δ=arctan(ω_(y)/ω_(x)). As an example, ifthe output beam 125 is scanned along scan axis Θ_(x) at an angularscanning speed ω_(x) of 72,000 degrees per second and along scan axisΘ_(y) at an angular scanning speed ω_(y) of 300 degrees per second, thenscan lines 410 may have an incline angle δ of approximately 4.2 mrad(or, approximately 0.24°). As another example, if ω is 10,000 degreesper second and ω_(y) is 350 degrees per second, then scan lines 410 mayhave an incline angle δ of approximately 2°, and each scan line 410 maybe oriented downward at 2° with respect to the Θ_(x) axis.

FIG. 11 illustrates an example scan pattern 200 with a nonuniformdistribution of scan lines 410. The scan pattern 200 illustrated in FIG.11 is similar to the scan pattern 200 illustrated in FIG. 8, except scanpattern 200 in FIG. 11 is a unidirectional scan pattern 200 where eachscan line 410 travels across the FOR in substantially the same direction(e.g., from left to right). The unidirectional, adjustable-density scanpattern 200 illustrated in FIG. 11 includes a higher density of scanlines 410 between angles Θ₁ and Θ₂ and a lower density of scan lines 410between angles Θ_(min) and Θ₁ and between angles Θ₂ and Θ_(max). Inparticular embodiments, the region of higher-density scan lines 410between angles Θ₁ and Θ₂ may be located or adjusted in any suitablemanner. As an example, the values of angles Θ_(min) and Θ_(max) may beapproximately −15° and +15°, respectively, and the values of Θ₁ and Θ₂may be approximately −2° and +2°, respectively, or approximately −5° and+3°, respectively. Additionally, the values of Θ₁ or Θ₂ may be updatedfrom one scan to another. As another example, the value of Θ₂-Θ₁ (whichrepresents an angular range of the higher-density scan region) may beapproximately 0.5°, 1°, 2°, 5°, 10°, or 20°, and the value of Θ₂-Θ₁ maybe updated from one scan to another.

FIG. 12 illustrates an example scan pattern 200 contained within anadjustable field of regard FOR′. In particular embodiments, a field ofregard (represented by FOR) may be referred to as a fixed field ofregard or a global field of regard, and an adjustable field of regard(represented by FOR′) may be referred to as a configurable field ofregard or a focused field of regard. An adjustable field of regard FOR′may refer to a field of regard that covers a portion of a fixed field ofregard or is contained within a fixed field of regard. In particularembodiments, a scan pattern 200 contained within an adjustable field ofregard FOR′ may be a focused scan pattern, a scan pattern with a uniformdistribution of scan lines 410, or a scan pattern with a nonuniformdistribution of scan lines 410. As an example, a nonuniform scan pattern200 similar to that shown in FIG. 11 may be contained within anadjustable field of regard FOR′ between the angles Θ′_(min) andΘ′_(max). In the example of FIG. 12, the adjustable field of regard FOR′contains a focused scan pattern with a substantially uniformdistribution of scan lines 410.

The maximum angle Θ_(max) and the minimum angle Θ_(min) (which may bereferred to as the fixed maximum angle and the fixed minimum angle,respectively) set the upper and lower limits of the fixed field ofregard along the Θ_(y) axis. The maximum and minimum angles of the FORmay be non-adjustable and may be determined by a maximum range overwhich a scanning mirror (e.g., mirror 300-2 in FIG. 4) is capable ofscanning along the Θ_(y) scan axis. The maximum scan angle Θ′_(max) andthe minimum scan angle Θ′_(min) of the adjustable field of regard FOR′may be referred to as the adjustable maximum scan angle (or adjustablemaximum angle) and the adjustable minimum scan angle (or adjustableminimum angle), respectively. The maximum and minimum angles of thefixed field of regard may be fixed or non-adjustable angular values, andthe maximum and minimum adjustable angles may be adjustable to anysuitable values located between the maximum and minimum angles of thefixed field of regard. An adjustable field of regard may cover orcoincide with a fixed field of regard for one or more scans performed byscanner 120 (e.g., Θ′_(max) may be approximately equal to Θ_(max), andΘ′_(min) may be approximately equal to Θ_(min)). For example, Θ_(max)may be +15°, and Θ_(min) may be −15°, and for one or more scansperformed by scanner 120, the angles Θ′_(max) and Θ′_(min) may be set to+15° and −15°, respectively (e.g., the FOR′ has approximately the sameextent as the FOR). For one or more subsequent scans, the anglesΘ′_(max) and Θ′_(min) may be adjusted to any suitable values such thatΘ_(max)≥Θ′_(max)>Θ′_(min)≥Θ_(min). For example, the angles Θ′_(max) andΘ′_(min) may be adjusted to +4° and −6°, respectively.

In particular embodiments, an adjustable field of regard may beadjustable along the Θ_(y) axis and may be fixed along the Θ_(x) axis.An adjustable field of regard may have an extent along the Θ_(x) axisthat is fixed and is approximately the same as the extent of the fixedfield of regard (e.g., a FOR and FOR′ may cover approximately the sameFOR_(H)). As an example, an adjustable field of regard may have a fixedhorizontal range of approximately 60°. In particular embodiments, anadjustable field of regard may include a non-adjustable field of regardalong the Θ_(x) scan axis that is greater than or equal to 40°. Forexample, the FOR′ in FIG. 12 may be fixed along the Θ_(x) scan axis withan extent along the Θ_(x) scan axis that is approximately equal toFOR_(H). In particular embodiments, an adjustable field of regard mayinclude an adjustable field of regard along the Θ_(y) scan axis that isbetween approximately 1° and approximately 40°. For example, the size ofthe FOR′ in FIG. 12 may be adjustable along the Θ_(y) scan axis so that(Θ′_(max)-Θ′_(min)) may be set to any suitable value from 1° to 40°.

In particular embodiments, an adjustable field of regard may cover ahorizontal swath or section of a fixed field of regard, where thehorizontal swath has a fixed horizontal extent and an adjustablevertical extent. For example, a fixed field of regard may cover a60-degree horizontal range and a 30-degree vertical range, and anadjustable field of regard may cover the same 60-degree horizontal rangeand a 10-degree vertical range within the 30-degree vertical range ofthe fixed field of regard. In the example of FIG. 12, the adjustablefield of regard FOR′ has approximately the same extent along the Θ_(x)axis as the fixed field of regard FOR. In particular embodiments, anadjustable field of regard may cover a vertical swath of a fixed fieldof regard. For example, a fixed field of regard may cover an 80-degreehorizontal range and a 40-degree vertical range, and an adjustable fieldof regard may cover the same 40-degree vertical range and a 20-degreehorizontal range within the 80-degree horizontal range.

In particular embodiments, a focused scan pattern may have an increaseddensity of scan lines 410 with respect to a standard scan pattern. As anexample, scan pattern 200 in FIG. 10 may have a scan-line density ofapproximately 2 scan lines per degree, and focused scan pattern 200 inFIG. 12 may have a scan-line density of approximately 8 scan lines perdegree. In particular embodiments, a focused scan pattern may have anincreased frame rate with respect to a standard scan pattern. As anexample, a standard scan pattern may have approximately 2 scan lines perdegree and a 10-Hz frame rate, and a focused scan pattern may haveapproximately 2 scan lines per degree and a 40-Hz frame rate. A focusedscan pattern may have one-fourth the number of scan lines as a standardscan pattern, and so, the focused scan pattern may be able to scan at afour-times faster frame rate. In particular embodiments, a focused scanpattern may have an increased density of scan lines 410 and an increasedframe rate with respect to a standard scan pattern. As an example, astandard scan pattern may have approximately 2 scan lines per degree anda 10-Hz frame rate, and a focused scan pattern may have approximately 4scan lines per degree and a 20-Hz frame rate.

In particular embodiments, a lidar system 100 may include a light source110 configured to emit pulses of light and a scanner 120 configured toscan at least a portion of the emitted pulses of light along a scanpattern 200 contained within an adjustable field of regard FOR′. Inparticular embodiments, a scanner 120 may include a first scanningmirror (e.g., polygon mirror 300-1 in FIG. 4) and a second scanningmirror (e.g., mirror 300-2 in FIG. 4). The first scanning mirror may bereferred to as a x-scan mirror, and the second scanning mirror may bereferred to as a y-scan mirror. The x-scan mirror may be configured toscan pulses of light substantially parallel to a scan axis Θ_(x) toproduce multiple scan lines 410 of the scan pattern 200, where each scanline 410 is oriented substantially parallel to the scan axis Θ_(x). They-scan mirror may be configured to distribute the scan lines 410 along ascan axis Θ_(y) that is substantially orthogonal to scan axis Θ_(x). InFIG. 3, scanner 120 includes x-scan mirror 300-1 and y-scan mirror300-2. Scanning mirror 300-1 oscillates back and forth to scan outputbeam 125 along scan axis Θ_(x) and produce multiple scan lines 410, andscanning mirror 300-2 is oscillated to distribute the scan lines 410along scan axis Θ_(y). In FIG. 4, scanner 120 includes x-scan mirror300-1 and y-scan mirror 300-2. Scanning mirror 300-1 is a polygon mirrorthat is rotated continuously to scan output beam 125 along scan axisΘ_(x) and produce multiple scan lines 410, and scanning mirror 300-2 isoscillated to distribute the scan lines 410 along scan axis Θ_(y).

In particular embodiments, scan lines 410 may be distributed within anadjustable field of regard FOR′ according to an adjustable Θ_(y)-axisscan profile, where the adjustable scan profile includes Θ′_(min) (theminimum scan angle along the Θ_(y) axis), Θ′_(max) (the maximum scanangle along the Θ_(y) axis), and a scan-line distribution. The scanlines 410 may be located between the minimum scan angle Θ′_(min) and themaximum scan angle Θ′_(max), and the scan-line distribution represents adistribution of scan lines 410 between the minimum and maximum scanangles and corresponds to one or more positions or one or more scanningspeeds of the y-scan mirror. The scan-line distribution represents howthe scan lines 410 are distributed along the Θ_(y) axis (e.g., evenlydistributed, or distributed with a variation in scan-line density), andthe scan-line distribution may be determined at least in part by thescanning speed of the y-scan mirror.

In particular embodiments, a scan-line distribution may represent orcorrespond to one or more scanning speeds of a y-scan mirror (e.g.,scanning mirror 300-2 in FIG. 3 or scanning mirror 300-2 in FIG. 4). Inparticular embodiments, the one or more scanning speeds of they-scanmirror may include a substantially constant scanning speed, and thecorresponding scan-line distribution may include scan lines 410 that arespaced apart substantially uniformly along the Θ_(y) scan axis. As anexample, scanning mirror 300-2 in FIG. 4 may be scanned at asubstantially constant scanning speed (e.g., 300 degrees per second),and the resulting scan lines 410 may have a substantially uniformspacing between them (e.g., as illustrated by the scan lines 410 in FIG.10 and FIG. 12). In particular embodiments, the one or more scanningspeeds of the y-scan mirror (e.g., mirror 300-2 in FIG. 4) may include alower scanning speed (e.g., 50 degrees per second) and a higher scanningspeed (e.g., 400 degrees per second). The corresponding scan-linedistribution may include a higher density of scan lines 410corresponding to the lower scanning speed and a lower density of scanlines 410 corresponding to the higher scanning speed. As an example,scanning mirror 300-2 in FIG. 4 may have an adjustable scanning speedand may be configured to produce a scan pattern 200 like that in FIG. 11with a region of higher-density scan lines 410 between angles Θ₁ and Θ₂and lower-density scan lines 410 outside that region.

In particular embodiments, a scan-line distribution may represent orcorrespond to one or more positions or angles of the y-scan mirror(e.g., scanning mirror 300-2 in FIG. 3 or scanning mirror 300-2 in FIG.4). In particular embodiments, the one or more positions of the y-scanmirror may include a beginning position and an ending position. As anexample, the beginning position may correspond to a scan line 410located approximately at a maximum scan angle Θ′_(max), and the endingposition may correspond to a scan line 410 located approximately at aminimum scan angle Θ′_(min). In the example of FIG. 12, scan line 410Xmay be associated with a beginning position of a scanning mirror, andscan line 410Y may be associated with an ending position of the scanningmirror. After scan line 410Y is scanned, the scanning mirror may performa retrace operation by moving from the ending position back to thebeginning position and then start a new scan. In particular embodiments,the one or more positions of the y-scan mirror may include one or morepositions of the y-scan mirror between a beginning and ending position.As an example, each scan line 410 of a scan pattern 200 may correspondto a particular position or angle of a scanning mirror. In the exampleof FIG. 11, each of the 11 scan lines 410 may correspond to a particularposition or angle of a scanning mirror, and these positions or anglesmay be specified by a scan-line distribution.

In particular embodiments, a scan pattern 200 as illustrated in FIG. 10,11, or 12 may be produced by a lidar system 100 that includes a scanner120 with a polygon mirror that includes two or more reflective surfaces320 (e.g., polygon mirror 300-1 in FIG. 4). The polygon mirror 300-1 inFIG. 4 may be configured to continuously rotate at a substantiallyconstant rotation speed (e.g., 150 revolutions per second) in onedirection about a rotation axis of the polygon mirror. Pulses of lightemitted by a light source 110 may be reflected sequentially from thereflective surfaces 320 as the polygon mirror 300-1 is rotated,resulting in the pulses of light begin scanned substantially parallel tothe first scan axis Θ_(x) to produce multiple scan lines 410, where eachscan line 410 corresponds to a reflection from one of the reflectivesurfaces 320.

In particular embodiments, the multiple scan lines 410 of a scan pattern200 may be distributed temporally based at least in part on a scanningspeed of a x-scan mirror. Each scan line 410 may be produced over aparticular time interval, and scan lines 410 may be producedsequentially so that their respective time intervals do not overlap. Asan example, scan line 410A in FIG. 10 may be produced during a timeinterval from 0 ms to 1 ms, and scan line 410B may be produced during asubsequent time interval from 1 ms to 2 ms. The respective scan lines410 of a scan pattern 200 may be produced sequentially in time so thatno two scan lines 410 are produced at the same time or over the sametime interval. For example, scan line 410A may be produced from 0.2 msto 0.8 ms, and scan line 410B may be produced from 1.2 ms to 1.8 ms(e.g., there is a 0.4-ms time gap between the two scan lines). Thescanning speed or the number of reflective surfaces 320 of the x-scanmirror may determine how the scan lines 410 are distributed in time. Forexample, the polygon mirror 300-1 in FIG. 4 with N=4 sides may have arotation speed R of 100 revolutions per second, corresponding toproducing approximately 400 scan lines per second (or, one scan lineevery 2.5 ms). Scan line 410A in FIG. 10 may then be produced during atime interval from 0 ms to 2.5 ms, and the subsequent scan line 410B maybe produced during a time interval from 2.5 ms to 5 ms. For example,scan line 410A may be produced from 0.5 ms to 2 ms, and scan line 410Bmay be produced from 3 ms to 4.5 ms.

In particular embodiments, a x-scan mirror may scan pulses of lightsubstantially parallel to a scan axis Θ_(x). and each scan line 410 maybe oriented substantially parallel to the scan axis Θ_(x). Each scanline 410 of a scan pattern 200 being oriented substantially parallel tothe scan axis Θ_(x) may refer to each scan line 410 being oriented towithin approximately 0°, 0.1°, 0.2°, 0.5°, 1°, 2°, 5°, or 10° of thescan axis Θ_(x). The scan-line orientation may correspond to the inclineangle δ as described above with respect to FIG. 10. As an example, thescan lines 410 in FIG. 10 may be referred to as being substantiallyparallel to the scan axis Θ_(x), and each scan line 410 may have anincline angle δ that is less than or equal to 5°. As another example,the scan lines 410 in FIG. 11 may be referred to as being substantiallyparallel to the scan axis Θ_(x), and each scan line 410 may have anincline angle δ that is between approximately 1° and approximately 5°.As another example, the scan lines 410 in FIG. 12 may be referred to asbeing substantially parallel to the scan axis Θ_(x), and each scan line410 may have an incline angle δ that is approximately equal to 0.5°. Inparticular embodiments, one or more scan lines 410 of a scan pattern 200may be a substantially straight line. In the example of FIGS. 10-12,each scan line 410 is a substantially straight line.

FIG. 13 illustrates an example scan pattern 200 with slightly curvedscan lines 410. In particular embodiments, one or more scan lines 410 ofa scan pattern 200 may be slightly curved or may have some amount ofcurvature. As an example, a scan line 410 may be slightly curved if eachsection of the scan line 410 has a slope or orientation that is within aparticular angular range (e.g., within 1°, 2°, 5°, or 10°) of the scanaxis Θ_(x). In FIG. 13, each scan line 410 has sections withorientations that are within approximately 5° of the scan axis Θ_(x).For example, each scan line 410 has a left section with an orientation(with respect to the scan axis Θ_(x)) of approximately +2.5°, a middlesection with an orientation of approximately 0°, and a right sectionwith an orientation of approximately −5°. In particular embodiments, ascan line 410 that is slightly curved may be referred to as beingoriented substantially parallel to a scan axis Θ_(x).

In particular embodiments, a scan pattern 200 may include any suitablenumber of scan lines 410. As an example, a scan pattern 200 may includefrom approximately 10 scan lines 410 to approximately 1,000 scan lines.In particular embodiments, the number of scan lines 410 in a scanpattern 200 may be adjustable. As an example, a lidar system 100 mayperform a high-resolution scan using a scan pattern 200 withapproximately 640 scan lines 410, and the lidar system 100 may perform asubsequent scan using a scan pattern 200 with approximately 64 scanlines 410.

In particular embodiments, each scan line 410 may extend fromapproximately one edge of the adjustable field of regard toapproximately an opposite edge of the adjustable field of regard. InFIGS. 7-11, each scan line 410 extends along scan axis Θ_(x) from a leftedge of the FOR to a right edge of the FOR. In particular embodiments,the edges of FOR and FOR′ which are approximately parallel to scan axisΘ_(y) may be approximately coincident. In FIGS. 12 and 13, the left andright edges of the FOR′ are approximately coincident with the respectiveleft and right edges of the FOR, and each scan line 410 extends from theleft edge of the FOR′ to the right edge of the FOR′.

FIG. 14 illustrates an example nonuniform scan pattern 200 with scanlines 410 oriented vertically. The scan pattern 200 illustrated in FIG.14 is a unidirectional scan pattern 200 where each scan line 410 travelsvertically across the FOR in substantially the same direction (e.g.,from top to bottom). In particular embodiments, scan axis Θ_(x) may havea substantially vertical orientation, and scan axis Θ_(y) may have asubstantially horizontal orientation. The scan pattern 200 in FIG. 14 issimilar to that of FIG. 11 with the orientation of the scan axes Θ_(x)and Θ_(y) reversed. Similarly, the orientation of the scan lines 410 inFIG. 14 is rotated by 90° with respect to the scan lines in FIG. 11. InFIG. 14, scan axis Θ_(y) corresponds to the horizontal field of regard(FOR_(H)) and may extend horizontally from −30 degrees to +30 degrees.Similarly, scan axis Θ_(x) corresponds to the vertical field of regard(FOR_(V)) and may extend vertically from −10 degrees to +10 degrees.

FIG. 15 illustrates an example focused scan pattern 200 with scan lines410 oriented vertically. In FIG. 15, the scan pattern 200 is containedwithin an adjustable field of regard FOR′ that extends along the Θ_(y)scan axis between the angles Θ′_(min) and Θ′_(max). Additionally, thetop and bottom edges of the FOR′ are approximately coincident with therespective top and bottom edges of the FOR. The scan pattern 200illustrated in FIG. 15 is similar to that of FIG. 12 with theorientation of the scan axes Θ_(x) and Θ_(y) reversed. Similarly, theorientation of the scan lines 410 in FIG. 15 is rotated by 90° withrespect to the scan lines in FIG. 12. Each scan line 410 extendsvertically across the full FOR_(V), and the scan pattern 200 covers aportion of the FOR along the Θ_(y) scan axis. A scan pattern 200 withscan lines 410 oriented vertically (as illustrated in FIG. 14 or 15) maybe produced by a lidar system 100 as illustrated in FIG. 4. The polygonmirror 300-1 may be configured to produce the vertically oriented scanlines 410, and the scanning mirror 300-2 may be configured to distributethe scan lines 410 horizontally along the Θ_(y) scan axis.

In particular embodiments, a Θ_(x) scan axis may be substantiallyhorizontal, and the corresponding Θ_(y) scan axis may be substantiallyvertical. Additionally, the adjustable minimum scan angle Θ′_(min) andthe adjustable maximum scan angle Θ′_(max) may each correspond to anelevation angle. In each of FIGS. 12 and 13, the Θ_(x) scan axis issubstantially horizontal, and the Θ_(y) scan axis is substantiallyvertical. Additionally, the angles Θ′_(min) and Θ′_(max) are elevationangles.

In particular embodiments, a Θ_(x) scan axis may be substantiallyvertical, and the corresponding Θ_(y) scan axis may be substantiallyhorizontal. Additionally, the adjustable minimum scan angle Θ′_(min) andthe adjustable maximum scan angle Θ′_(max) may each correspond to anazimuth angle. In each of FIGS. 14 and 15, the Θ_(x) scan axis issubstantially vertical, and the Θ_(y) scan axis is substantiallyhorizontal. Additionally, in FIG. 15, the angles Θ′_(min) and Θ′_(max)are azimuth angles.

FIG. 16 illustrates an example scan profile 500 for a scan pattern 200with a substantially uniform distribution of scan lines 410. Inparticular embodiments, a scan profile 500 may be referred to as aΘ_(y)-axis scan profile, a y-axis scan profile, an adjustable scanprofile, an adjustable Θ_(y)-axis scan profile, an adjustable y-axisscan profile, or a scan-pattern y-component. In particular embodiments,a scan profile 500 may represent the position of a scanning mirror(e.g., mirror 300-2 in FIG. 3 or FIG. 4) versus time, or a scan profile500 may represent the position of an output beam 125 along the Θ_(y)scan axis versus time. In particular embodiments, a scan profile 500 maycorrespond to the Θ_(y)-axis portion of a scan where a scanner 120directs an output beam 125 across a scan pattern 200 from a startingpoint 430A to an end point 430B, and a retrace 400 may represent theportion of a scan where the scanner 120 resets to the starting point ofthe scan. For example, the scan profile 500 illustrated in FIG. 16 maycorrespond to the scan pattern 200 in FIG. 7 which includes traversingthe scan pattern 200 from starting point 430A to end point 430B and aretrace 400 from end point 430B to starting point 430A.

The y-axis scan time τ_(y) corresponds to a time for the output beam 125to be scanned across a scan pattern 200 from a starting point 430A to anend point 430B (not including the time to perform a retrace 400). Forexample, they-axis scan time τ_(y) may correspond to a time for scanningmirror 300-2 in FIG. 3 or FIG. 4 to scan the output beam 125 from amaximum angle (e.g., Θ_(max) or Θ′_(max)) to a minimum angle (e.g.,Θ_(min) or Θ′_(min)). The retrace time τ_(retrace) corresponds to a timefor the output beam 125 to traverse the retrace path 400 (e.g., from anend point back to a starting point). The time τ_(scan) corresponds tothe total time to scan one complete round-trip of a scan pattern 200(e.g., from a starting point to an end point, and then retracing back tothe starting point), and τ_(scan) equals τ_(y)+τ_(retrace). The framerate F at which a lidar system 100 scans may be expressed as 1/τ_(scan)which is equal to 1/(τ_(y)+τ_(retrace)). A lidar system 100 may have anysuitable scan time τ_(scan), such as for example, a scan time ofapproximately 10 s, 2 s, 1 s, 0.5 s, 0.2 s, 100 ms, 50 ms, 10 ms, or 1ms.

The scan profile 500 illustrated in FIG. 16 may correspond to the scanpattern 200 illustrated in FIG. 7 or FIG. 10. In particular embodiments,a slope of scan profile 500 may correspond to an angular scan speedalong the Θ_(y) scan axis. For example, the slope of the scan profile500 in FIG. 16 may be approximately 300 degrees per second, and this maycorrespond to a substantially constant scan speed (e.g., of output beam125 along the Θ_(y) scan axis) of approximately 300 degrees per second.The substantially uniform distribution of scan lines 410 in FIGS. 7 and10 corresponds to the substantially uniform slope of the scan profile500. Since the slope of the scan profile 500 is substantially constant(corresponding to a substantially uniform scan speed), the scan lines410 in FIGS. 7 and 10 are spaced apart along the Θ_(y) scan axis in asubstantially uniform manner. In particular embodiments, a scan profile500 may include any suitable slope or combination of two or more slopes,which corresponds to any suitable scan speed or combination of two ormore scan speeds.

FIG. 17 illustrates an example scan profile 500 for a scan pattern 200with a nonuniform distribution of scan lines 410. The scan profile 500illustrated in FIG. 17 may correspond to the scan pattern 200illustrated in FIG. 8, FIG. 11, or FIG. 14. For example, the lowerdensity of scan lines 410 between angles Θ_(min) and Θ_(max) and betweenangles Θ₂ and Θ_(max) may be associated with the higher slope of thescan profile 500 between those angles (and a corresponding higher scanspeed). Similarly, the higher density of scan lines 410 between anglesΘ₁ and Θ₂ may be associated with the lower slope of the scan profile 500between those angles (and a corresponding lower scan speed). Anadjustable scan profile 500 as illustrated in FIG. 17 may be produced bya scanning mirror (e.g., mirror 300-2 in FIG. 3 or FIG. 4) having anadjustable scan rate along the Θ_(y) scan axis. Between angles Θ_(min)and Θ₁ and between angles Θ₂ and Θ_(max), the scan profile 500 may havea slope of approximately 400 degrees per second (which corresponds to ascan rate along the Θ_(y) scan axis of approximately 400 degrees persecond). Additionally, between angles Θ₁ and Θ₂, the scan profile 500may have a slope of approximately 50 degrees per second.

FIG. 18 illustrates an example scan profile 500 associated with afocused scan pattern. The scan profile 500 illustrated in FIG. 18 maycorrespond to the scan pattern 200 illustrated in FIG. 12, FIG. 13, orFIG. 15, where the scan pattern 200 is contained within an adjustablefield of regard FOR′. The scan profile 500 in FIG. 18 represents a scanpattern 200 that scans output beam 125 along the Θ_(y) scan axis betweenthe angles Θ′_(min) and Θ′_(max). The scan profile 500 illustrated inFIG. 18 has a substantially constant slope corresponding to asubstantially uniform scan speed and a substantially uniformdistribution of scan lines 410 between the angles Θ′_(min) and Θ′_(max)(e.g., as illustrated by the scan lines 410 in FIG. 12). In particularembodiments, a scan profile 500 for a focused scan pattern may includeany suitable slope or combination of two or more slopes. As an example,a scan profile 500 located between the angles Θ′_(min) and Θ′_(max) mayinclude one section with a higher slope (corresponding to a higherscanning speed and a lower density of scan lines 410) and anothersection with a lower slope (corresponding to a lower scanning speed anda higher density of scan lines 410). As another example, a scan profile500 similar to that in FIG. 17 may be located between the anglesΘ′_(min) and Θ′_(max) of an adjustable field of regard FOR′.

In particular embodiments, a scan profile 500 may include or may bebased on a minimum scan angle (e.g., Θ_(min) or Θ′_(min)) and a maximumscan angle (e.g., Θ_(max) or Θ′_(max)). In the example of FIG. 16 andFIG. 17, the scan profile 500 extends from the maximum scan angleΘ_(max) to the minimum scan angle Θ_(min). In the example of FIG. 18,the scan profile 500 extends from the adjustable maximum angle Θ′_(max)to the adjustable minimum angle Θ′_(min). In particular embodiments, ascan profile 500 may include or may be based on a scan-line distributionwhich represents a distribution of scan lines 410 between a minimum scanangle (e.g., Θ_(min) or Θ′_(min)) and a maximum scan angle (e.g.,Θ_(max) or Θ′_(max)). The scan lines 410 may be distributed or arrangedalong the Θ_(y) scan axis and within the adjustable field of regard inany suitable manner. A scan-line distribution may include one or moreslopes of the scan profile 500 or one or more scanning speeds of amirror configured to scan along the Θ_(y) scan axis.

In particular embodiments, a scan profile 500 may be repeated anysuitable number of times. As an example, a particular scan profile 500may be repeated 1, 2, 5, 10, 100, 1,000, 10,000, or any other suitablenumber of times (e.g., a lidar system 100 may perform 50 scans insuccession using the scan profile 500 illustrated in FIG. 17). Inparticular embodiments, a scan profile 500 may be changed or adjustedbetween scans. As an example, a lidar system 100 may perform anysuitable number of scans using scan profile 500 illustrated in FIG. 16,and then the lidar system 100 may switch to the scan profile 500illustrated in FIG. 18. In particular embodiments, a scan profile 500may be adjusted between subsequent scans in any suitable manner. As anexample, a minimum scan angle (e.g., Θ_(min) or Θ′_(min)), a maximumscan angle (e.g., Θ_(max) or Θ′_(max)), or a scan-line distribution maybe adjusted in any suitable manner.

In particular embodiments, a lidar system 100 may include a processorconfigured to adjust a Θ_(y)-axis scan profile 500. For example, aprocessor configured to adjust a scan profile 500 may include anysuitable processor located within the lidar system 100 (e.g., theprocessor may include or may be part of controller 150) or locatedexternal to the lidar system 100. In particular embodiments, a processormay be configured to adjust a Θ_(y)-axis scan profile 500 after a lidarsystem 100 captures one or more initial frames, and the adjustedΘ_(y)-axis scan profile 500 may be applied to one or more subsequentframes that are captured after the initial frames. In particularembodiments, a processor may be configured to adjust a Θ_(y)-axis scanprofile 500 in response to detecting pulses of light scattered by atarget 130. The Θ_(y)-axis scan profile 500 may be adjusted to provide ascan of the target 130 that has a higher resolution (e.g., a higherdensity of scan lines 410) or a higher frame rate than a previous scan.For example, a lidar system may use scan profile 500 in FIG. 16 to scana field of regard. After a target 130 is detected in a particularportion of the field of regard, the processor may adjust the Θ_(y)-axisscan profile 500 to focus on that portion of the field of regard wherethe target 130 is located. For example, the processor may select scanprofile 500 illustrated in FIG. 17 (e.g., at least part of the target130 is located between angles Θ₁ and Θ₂) or scan profile 500 illustratedin FIG. 18 (e.g., at least part of the target 130 is located betweenangles Θ′_(min) and Θ′_(max)).

In particular embodiments, adjusting a Θ_(y)-axis scan profile 500 mayinclude adjusting a minimum or maximum scan angle to reduce an angularrange of an adjustable field of regard along the Θ_(y) scan axis. Theangular range of an adjustable field of regard may be expressed asΘ′_(max)-Θ′_(min) and may have any suitable value, such as for example,0.5°, 1°, 2°, 5°, 10°, 20°, 30°, 40°, or 50°. In particular embodiments,the angular range of an adjustable field of regard may be reduced sothat a lidar system 100 scans a particular region of interest with anincreased density of scan lines 410. As an example, a scanner 120 may beconfigured to scan using scan profile 500 illustrated in FIG. 16, andfor a subsequent scan, the scan profile 500 may be adjusted so that thescanner 120 scans using the scan profile 500 illustrated in FIG. 18. Forexample, in FIG. 16, Θ_(max) may be +15° and Θ_(min) may be −15°,corresponding to a 30° angular range. In FIG. 18, the maximum andminimum scan angles (Θ′_(max) and Θ′_(min)) may be adjusted to +5° and−5°, respectively, corresponding to a reduced angular range of 10°.Additionally, the scan speed (corresponding to the slope of the scanprofile) may be reduced when scanning across a reduced angular range,which results in an increase in scan-line density for the reducedangular range. For example, the scan speed may be reduced by a factor of3, resulting in a 3× increase in the scan-line density for the reducedangular range. As another example, a scanner 120 may be configured toscan using scan profile 500 in FIG. 18, and for a subsequent scan, theangles Θ′_(min) and Θ′_(min) may be adjusted to focus on a particularregion of interest. For example, in FIG. 18, Θ′_(max) may be +10° andΘ′_(min) may be −10°, corresponding to a 20° angular range. The maximumand minimum scan angles (Θ′_(max) and Θ′_(min)) may be adjusted to +2°and −6°, respectively, corresponding to a reduced angular range of 8°.

In particular embodiments, the angular range of an adjustable field ofregard may be reduced so that a lidar system 100 scans a particularregion of interest with an increased frame rate. As an example, ascanner 120 may be adjusted to scan over a reduced angular range, andthe scan speed may not be reduced (or the scan speed may be reduced by afactor less than the reduction in the angular range). If the angularscan range along the Θ_(y) scan axis is reduced by a factor of 4 and thescan speed remains substantially unchanged, then the frame rate willincrease by approximately a factor of 4, and the scan-line density willremain substantially unchanged. For example, a scan over a 30° scanrange may be performed in a scan time τ_(y) of approximately 100 ms andmay include approximately 64 scan lines 410. The angular range may bereduced by 4× to a 7.5° scan range, and, if the scan speed is notchanged, then the scan time τ_(y) will be reduced to approximately 25ms, and the scan will include approximately 16 scan lines 410. Thescan-line density for both the 30° scan and the 7.5° scan will beapproximately 2.1 scan lines per degree.

In particular embodiments, the angular range of an adjustable field ofregard may be reduced so that a lidar system 100 scans a particularregion of interest with an increased frame rate and an increasedscan-line density. As an example, if an angular scan range along theΘ_(y) scan axis is reduced by a factor of 4 and the scan speed isreduced by a factor of 2, then the frame rate will increase byapproximately a factor of 2, and the scan-line density will increase byapproximately a factor of 2. For example, a scan over a 20° scan rangemay be performed in a scan time τ_(y) of approximately 100 ms and mayinclude approximately 64 scan lines 410 (corresponding to a scan-linedensity of approximately 3.2 scan lines per degree). The angular rangemay be reduced by 4× to a 5° scan range, and the scan speed may bereduced by 2× so that the scan time τ_(y) is approximately 50 ms(corresponding to an increase in the frame rate of approximately 2×).The reduced scan may include approximately 32 scan lines 410, and thescan-line density may be approximately 6.4 scan lines per degree(corresponding to a 2× increase in scan-line density).

In particular embodiments, adjusting a Θ_(y)-axis scan profile 500 mayinclude adding an angular-offset value ΔΦ to each of the minimum andmaximum scan angles to shift the adjustable field of regard along theΘ_(y) scan axis by the angular-offset value ΔΦ. As an example, a scanner120 may be configured to scan using scan profile 500 illustrated in FIG.18, and for a subsequent scan, the scan profile 500 may be adjusted sothat the scan lines 410 are moved up or down by an angular-offset valueΔΦ. For example, in FIG. 18, Θ′_(max) may be +5° and Θ′_(min) may be−5°. The scan-profile angles may be adjusted upwards by ΔΦ=2° resultingin an adjusted scan profile 500 where Θ′_(max) is +7° and Θ′_(min) is−3°.

In particular embodiments, adjusting a Θ_(y)-axis scan profile 500 mayinclude adding an angular-offset value ΔΦ₁ to a maximum scan angle andadding an angular-offset value ΔΦ₂ to a minimum scan angle. As anexample, a scanner 120 may be configured to scan using scan profile 500illustrated in FIG. 18, and for a subsequent scan, the scan profile 500may be adjusted so that Θ′_(max) is adjusted by ΔΦ₁, and Θ′_(min) isadjusted by ΔΦ₂. For example, in FIG. 18, Θ′_(max) may be +10° andΘ′_(min) may be −10°. The scan-profile angles may be adjusted by ΔΦ₁=−7°and ΔΦ₂=5° resulting in an adjusted scan profile 500 where Θ′_(max) is+3° and Θ′_(min) is −5°.

In particular embodiments, adjusting a Θ_(y)-axis scan profile 500 mayinclude adjusting a scan-line distribution to produce an increaseddensity of scan lines 410 for a particular region of interest. As anexample, a scanner 120 may be configured to scan using scan profile 500illustrated in FIG. 16, and for a subsequent scan, an adjusted scanprofile 500 based on FIG. 17 may be applied. The scan-line distributionmay be adjusted to provide a reduced scan speed between angles Θ₁ and Θ₂and a corresponding increase in scan-line density in that region. Asanother example, a scanner 120 may be configured to use scan profile 500illustrated in FIG. 18, and for a subsequent scan, the scan profile 500may be adjusted to provide a reduced scan speed between angles Θ′_(max)and Θ′_(min) (and a corresponding increase in scan-line density).

FIG. 19 illustrates an example scan profile 500 and a correspondingangular scanning-speed curve 510. In particular embodiments, a scanprofile 500 may include one or more piecewise linear sections or one ormore substantially smooth or continuous curves. The scan profile 500illustrated in FIG. 19 includes a smooth, continuous curve thatcorresponds to a smoothed version of the piecewise-linear scan profile500 in FIG. 17. The scanning-speed curve 510 in FIG. 19 represents theangular scanning speed (ω_(y)) of output beam 125 along the Θ_(y) scanaxis and is proportional to the first derivative with respect to time ofthe scan profile 500. Around time t₁, the scanning speed is reduced fromω₂ to ω₁, and around time t₂, the scanning speed increases from ω₁ toω₂. Rather than changing abruptly or instantaneously between the twoscanning speeds ω₁ and ω₂, the scanning speed transitions smoothlybetween them. As an example, an output beam 125 may transition from a200 degrees/second scan speed along the Θ_(y) scan axis to a 100degrees/second scan speed over a time interval of approximately 50-500μs. In particular embodiments, a scan profile 500 may include a slopethat varies in a continuous manner (corresponding to a scan speed thatalso varies in a continuous manner). As an example, a scan profile 500may include two sections with different slopes (corresponding to twodifferent scan speeds), and the two sections may be connected togetherby a smooth, monotonic curve that represents a substantially continuoustransition between the two slopes (corresponding to a substantiallysmooth transition from one scan speed to the other). In particularembodiments, a substantially smooth scan profile 500 or scanning-speedcurve 510 may correspond to the motion of a scanning mirror (e.g.,mirror 300-2 in FIG. 3 or FIG. 4) which may change its scan speed in asubstantially smooth manner rather than in an abrupt or instantaneousmanner.

FIG. 20 illustrates an example dual-direction scan profile 500. The scanprofile 500 in FIG. 20 includes a forward-scan profile 500A and areverse-scan profile 500B. In particular embodiments, a scan profile 500may not include a retrace 400, and the output beam 125 may becontinuously scanned back-and-forth between the minimum and maximum scanangles (e.g., between angles Θ_(max) and Θ_(min) or between anglesΘ′_(max) and Θ′_(min)). In the example of FIG. 20, scan profile 500Acorresponds to scan profile 500 in FIG. 16 where the output beam 125 isscanned along the Θ_(y) scan axis from Θ_(max) to Θ_(min). At the end ofscan profile 500A, rather than performing a retrace operation, theoutput beam 125 is scanned in the reverse direction along reverse-scanprofile 500B from Θ_(min) to Θ_(max). The lidar system 100 illustratedin FIG. 4 may perform a dual-direction scan by continuously rotating thepolygon mirror 300-1 and scanning the output beam 125 along adual-direction scan profile 500 as illustrated in FIG. 20. Eachtraversal of forward-scan profile 500A or reverse-scan profile 500Bresults in a complete scan of a scan pattern.

FIGS. 21-23 each illustrate an example vehicle 520 with a lidar system100 configured to produce a particular scan pattern 200. The examplescan pattern 200 illustrated in FIG. 21 is similar to scan pattern 200illustrated in FIG. 10 or FIG. 12, where the scan lines 410 aredistributed substantially evenly along the Θ_(y) scan axis. In FIG. 21,scan line 410E represents a scan line oriented at a maximum angle (e.g.,Θ_(max) or Θ′_(max)), and scan line 410F represents a scan line orientedat a minimum angle (e.g., Θ_(min) or Θ′_(min)). The example scan pattern200 illustrated in FIG. 22 is similar to scan pattern 200 illustrated inFIG. 11, where each scan pattern 200 has a variation in scan-linedensity along the Θ_(y) scan axis. In FIG. 22, scan line 410G representsa scan line oriented at a maximum angle (e.g., Θ_(max) or Θ′_(max)), andscan line 410H represents a scan line oriented at a minimum angle (e.g.,Θ_(min) or Θ′_(min)). Additionally, the region with a higher scan-linedensity (between scan lines 410I and 410J) corresponds to the regionbetween angles Θ₂ and Θ₁ in FIG. 11. The example scan pattern 200illustrated in FIG. 23 is similar to scan pattern 200 illustrated inFIG. 12, where each scan pattern is contained within an adjustable fieldof regard. In FIG. 23, scan line 410K represents a scan line oriented atan adjustable maximum angle Θ′_(max) (similar to scan line 410X in FIG.12), and scan line 410L represents a scan line oriented at an adjustableminimum angle Θ′_(min) (similar to scan line 410Y in FIG. 12).Additionally, the upper and lower dashed lines in FIG. 23 correspond tothe upper and lower limits along the Θ_(y) axis for a fixed field ofregard (e.g., Θ′_(max) and Θ′_(min), respectively).

FIGS. 24-25 each illustrate an example scan pattern 200 to which one ormore angular offsets are applied. In FIG. 24, an angular-offset value ΔΦis added to each of the minimum and maximum scan angles to shift thescan pattern 200 along the Θ_(y) scan axis by the angular-offset valueΔΦ. For the initial scan pattern 200, scan line 410M represents a scanline oriented at a maximum angle (e.g., Θ′_(max)), and scan line 410Nrepresents a scan line oriented at a minimum angle (e.g., Θ′_(min)). Forthe shifted scan pattern 200′, scan line 410M′ represents a scan lineoriented at a shifted maximum angle equal to Θ′_(max)+ΔΦ, and scan line410N′ represents a scan line oriented at a shifted minimum angle equalto Θ′_(min)+ΔΦ. In particular embodiments, an angular-offset value ΔΦmay have any suitable angular value, such as for example, approximately±0.2°, ±0.5°, ±1°, ±2°, ±5°, ±10°, ±20°, or ±30°. In the example of FIG.24, the angular-offset value ΔΦ is approximately +6°, and the scanpattern 200 is shifted up by approximately 6 degrees. The same angularoffset ΔΦ is applied to both the maximum and minimum angles, and theinitial scan pattern 200 and the shifted scan pattern 200′ both haveapproximately the same angular range (e.g., approximately 20°).

In FIG. 25, angular-offset value ΔΦ₁ is added to the maximum scan angle,and angular-offset value ΔΦ₂ is added to the minimum scan angle. For theinitial scan pattern 200, scan line 410P represents a scan line orientedat a maximum angle (e.g., Θ′_(max)), and scan line 410Q represents ascan line oriented at a minimum angle (e.g., Θ′_(min)). For the adjustedscan pattern 200′, the scan lines at the maximum and minimum angles areoffset by the angular-offset values ΔΦ₁ and ΔΦ₂, respectively, toproduce the shifted scan lines 410P′ and 410Q′. In the example of FIG.25, the angular-offset values ΔΦ₁ and ΔΦ₂ are approximately −6° and +6°,respectively. The initial scan pattern 200 has an angular range ofapproximately 26°, and the adjusted scan pattern 200′ has an angularrange of approximately 14°. In particular embodiments, angular-offsetvalues ΔΦ₁ and ΔΦ₂ may be set to any suitable angular values, and theadjusted scan pattern 200′ may be larger, smaller, or approximately thesame size as the initial scan pattern 200. Additionally, the adjustedscan pattern 200′ may be shifted up or down with respect to the initialscan pattern 200.

In particular embodiments, a lidar system 100 may include a processorconfigured to adjust a Θ_(y)-axis scan profile 500 based at least inpart on a driving condition of a vehicle 520 in which the lidar system100 is operating. In particular embodiments, a driving condition thattriggers adjustment of a Θ_(y)-axis scan profile may include detectionof a target 130 within the adjustable field of regard of the lidarsystem 100. As an example, a lidar system 100 in a vehicle 520 mayoperate with a scan pattern 200 based on FIG. 21. After a target 130 isdetected, the scan pattern 200 may be adjusted to that of FIG. 22 (whereat least part of the target 130 is located between scan lines 410I and410J) or FIG. 23 (where at least part of the target 130 is locatedbetween scan lines 410K and 410L). As another example, a lidar system100 may operate using scan pattern 200 illustrated in FIG. 25, and aftera target 130 is detected, the maximum and minimum angles may be adjustedto produce the adjusted scan pattern 200′. The adjusted scan pattern200′ may have a higher scan-line density or a higher frame rate than theinitial scan pattern 200. Scanning a target 130 with an adjusted scanpattern 200′ may allow the lidar system 100 to provide information aboutthe target 130 that has an increased spatial resolution (e.g., a higherdensity of scan lines 410) or an increased temporal resolution (e.g., ahigher frame rate).

In particular embodiments, a driving condition that triggers adjustmentof a Θ_(y)-axis scan profile 500 may include a grade of a road on whichthe vehicle 520 is operating or a change in the grade of a road on whichthe vehicle 520 is operating. The grade of a road represents the slopeof a road and may be referred to as a gradient, incline, pitch, rise, orslope. As an example, if the road ahead begins to slope upward (e.g.,there is an uphill section ahead), then the lidar system 100 may apply acorresponding upward angular offset ΔΦ to shift the scan pattern upward(e.g., as illustrated in FIG. 24). As another example, if the road aheadbegins to slope downward (e.g., there is a downhill section ahead), thenthe lidar system 100 may apply a downward angular offset to shift thescan pattern downward).

FIG. 26 illustrates an example scan pattern 200 with 16 scan lines (scanline 410-1 through scan line 410-16). In particular embodiments, a scanpattern 200 may be a non-interlaced scan pattern 200, where the scanlines 410 are scanned sequentially. A sequential scan of a series ofscan lines 410 may refer to the scan lines 410 being scanned in order oftheir respective spatial position. For example, scanner 120 may beconfigured to scan a series of scan lines 410 in order from left toright or from top to bottom. As another example, a non-interlaced scanpattern 200 may include three adjacent scan lines 410 (e.g., in order oftheir spatial position, a first scan line, a second scan line, and athird scan line), where the second scan line is scanned after the firstscan line, and the third scan line is scanned after the second scanline. Scan pattern 200 illustrated in FIG. 26 may be a non-interlacedscan pattern 200 where a scan begins with scan line 410-1 and ends withscan line 410-16. In FIG. 26, the scan lines may be scanned in orderfrom scan line 410-1 to scan line 410-16 to form a full-resolution scanof a FOR or FOR′. For example, scan line 410-1 may be scanned first,followed by scan line 410-2, then scan line 410-3, and so on until scanline 410-16 is scanned. In particular embodiments, a non-interlaced scanpattern 200 (which may be referred to as a sequential scan pattern) mayinclude any suitable number of scan lines 410, such as for example,approximately 5, 10, 20, 50, 100, 200, or 500 scan lines 410. Inparticular embodiments, a non-interlaced scan pattern 200 may cover allor part of a fixed field of regard or may cover all or part of anadjustable field of regard.

FIGS. 27-28 each illustrate one part of an example 2-fold interlacedscan pattern. In particular embodiments, an interlaced scan pattern mayinclude two or more parts (e.g., scan patterns 200A and 200B), and eachpart may be referred to as a sub-scan, a sub-cycle, a partial scan, alow-resolution scan, a high-frequency scan, or a high frame-rate scan.The two sub-scans illustrated in FIGS. 27-28 (scan pattern 200A and scanpattern 200B) together may represent an interlaced scan pattern thatcorresponds to the full-resolution scan pattern 200 illustrated in FIG.26. Scan pattern 200A in FIG. 27 includes the odd-numbered scan lines(scan lines 410-1, 410-3, 410-5, 410-7, 410-9, 410-11, 410-13, and410-15) from scan pattern 200 in FIG. 26. Scan pattern 200B in FIG. 28includes the even-numbered scan lines (scan lines 410-2, 410-4, 410-6,410-8, 410-10, 410-12, 410-14, and 410-16) from scan pattern 200 in FIG.26.

In FIG. 27, the dashed lines represent the even-numbered scan lines fromscan pattern 200B. For example, the dashed line between adjacent scanlines 410-1 and 410-3 in FIG. 27 represents scan line 410-2 in FIG. 28.Similarly, in FIG. 28, the dashed lines represent the odd-numbered scanlines from scan pattern 200A. For example, the dashed line betweenadjacent scan lines 410-2 and 420-4 in FIG. 28 represents scan line410-3 in FIG. 27. Each dashed line in FIGS. 27 and 28 represents a scanline that is part of an interlaced scan pattern but is not scanned inthat particular sub-scan. The dashed lines in FIG. 27 represent scanlines that are not scanned in scan pattern 200A but are scanned in scanpattern 200B. Similarly, the dashed lines in FIG. 28 represent scanlines that are not scanned in scan pattern 200B but are scanned in scanpattern 200A.

FIGS. 29-32 each illustrate one part of an example 4-fold interlacedscan pattern. The four sub-scans (scan patterns 200-1, 200-2, 200-3, and200-4) together may represent an interlaced scan pattern thatcorresponds to the full-resolution scan pattern 200 illustrated in FIG.26. Each sub-scan in FIGS. 29-32 starts with a particular scan line fromscan pattern 200 in FIG. 26 and includes every succeeding fourth scanline. Scan pattern 200-1 in FIG. 29 (which may start with scan line410-1 or 410-13) includes scan lines 410-1, 410-5, 410-9, and 410-13from scan pattern 200 in FIG. 26. Scan pattern 200-2 in FIG. 30 (whichmay start with scan line 410-2 or 410-14) includes scan lines 410-2,410-6, 410-10, and 410-14 from scan pattern 200 in FIG. 26. Scan pattern200-3 in FIG. 31 includes scan lines 410-3, 410-7, 410-11, and 410-15from scan pattern 200 in FIG. 26. Scan pattern 200-4 in FIG. 32 includesscan lines 410-4, 410-8, 410-12, and 410-16 from scan pattern 200 inFIG. 26.

In FIGS. 29-32, each pair of adjacent scan lines in a particularsub-scan is separated by three scan lines (represented by dashed lines)from other sub-scans. Each dashed line in FIGS. 29-32 represents a scanline that is part of an interlaced scan pattern but is not scanned inthat particular sub-scan. The dashed lines in FIG. 29 represent scanlines that are not scanned in scan pattern 200-1 but are scanned in scanpatterns 200-2, 200-3, and 200-4. For example, the three dashed linesbetween adjacent scan lines 410-1 and 410-5 represent scan line 410-2 inFIG. 30, scan line 410-3 in FIG. 31, and scan line 410-4 in FIG. 32. Asanother example, in FIG. 32, the three dashed lines between adjacentscan lines 410-12 and 410-16 represent scan line 410-13 in FIG. 29, scanline 410-14 in FIG. 30, and scan line 410-15 in FIG. 31.

In particular embodiments, an interlaced scan pattern may refer to ascan pattern where the scan lines 410 are scanned in a non-sequentialorder (e.g., the scan lines are scanned in an order that differs from aspatial arrangement of the scan lines). An interlaced scan pattern maybe referred to as a non-sequential scan pattern or an interleaved scanpattern. In particular embodiments, an interlaced scan pattern mayinclude two or more sub-scans, where each sub-scan of the interlacedscan pattern represents a subset or a part of a full-resolution scan.Each sub-scan includes scan lines 410 that are interlaced with (e.g.,located adjacent to or between) scan lines 410 of the other sub-scans.While the scan lines of an interlaced scan pattern may be scanned in anon-sequential manner, the scan lines of each sub-scan may be scannedsequentially according to the spatial arrangement of the scan lines inthat sub-scan. For example, the scan lines of sub-scan 200-1 illustratedin FIG. 29 may be scanned in the following order: 410-1, 410-5, 410-9,410-13.

In particular embodiments, the sub-scans of an interlaced scan patternmay be scanned in a particular order (e.g., scan pattern 200B may bescanned after scan pattern 200A is scanned), and each sub-scan may beused to generate a partial-resolution point cloud. Additionally, thepixels 210 or point clouds from each of the sub-scans may be combinedtogether to produce a full-resolution point cloud. Thepartial-resolution point clouds may have a lower resolution than thefull-resolution point cloud, but a series of partial-resolution pointclouds may be produced at a higher frame rate than the full-resolutionpoint cloud.

In FIGS. 27-28, scan patterns 200A and 200B together may represent aninterlaced scan pattern that corresponds to the full-resolution scanpattern 200 illustrated in FIG. 26. When scan patterns 200A and 200B arescanned in series, each scan of scan pattern 200A and 200B may be usedto generate a corresponding partial-resolution point cloud.Additionally, successive scans of scan patterns 200A and 200B may becombined together to form a full-resolution point cloud corresponding toscan pattern 200 in FIG. 26. Similarly, scan patterns 200-1, 200-2,200-3, and 200-4 together may represent an interlaced scan pattern thatcorresponds to scan pattern 200 illustrated in FIG. 26. The scanpatterns 200-1, 200-2, 200-3, and 200-4 may be scanned sequentially toproduce a series of partial-resolution point clouds, where eachpartial-resolution point cloud corresponds to one of the sub-scans.Additionally, the pixels 210 or point clouds obtained from each of thefour sub-scans 200-1, 200-2, 200-3, and 200-4 may be combined togetherto form a full-resolution point cloud corresponding to scan pattern 200in FIG. 26.

In particular embodiments, an interlaced scan pattern may include anysuitable number of sub-scans, such as for example, 2, 3, 5, 10, 20, or50 sub-scans. FIGS. 27-28 represent an interlaced scan pattern thatincludes 2 sub-scans, and FIGS. 29-32 represent an interlaced scanpattern that includes 4 sub-scans. In particular embodiments, thesub-scans of an interlaced scan pattern may be scanned in any suitablesequence or order. For example, the four sub-scans illustrated in FIGS.29-32 may be scanned in the following order: 200-1, 200-2, 200-3, 200-4.As another example, the four sub-scans may be scanned in the followingorder: 200-1, 200-3, 200-2, 200-4. In particular embodiments, aninterlaced scan pattern may be scanned repeatedly using a particularsequence. For example, the four sub-scans in FIGS. 29-32 may berepeatedly scanned using the same sequence (e.g., 200-1, 200-2, 200-3,200-4). In particular embodiments, an interlaced scan pattern may bescanned repeatedly using two or more particular sequences. For example,the four sub-scans in FIGS. 29-32 may scanned first with one sequence(e.g., 200-1, 200-2, 200-3, 200-4) and then with a different sequence(e.g., 200-4, 200-3, 200-2, 200-1). In particular embodiments, scanningthe sub-scans of an interlaced scan pattern in sequence may refer toscanning the sub-scans such that a succeeding sub-scan begins only aftera preceding sub-scan is completed.

In particular embodiments, an interlaced scan pattern may include anysuitable number of scan lines 410 distributed between any suitablenumber of sub-scans. As an example, an interlaced scan pattern mayinclude 64 scan lines 410 distributed between two sub-scans (e.g., eachsub-scan may include 32 scan lines) or distributed between foursub-scans (e.g., each sub-scan may include 16 scan lines). FIGS. 27-28represent an interlaced scan pattern with 16 scan lines distributedbetween two sub-scans (sub-scans 200A and 200B), and FIGS. 29-32represent an interlaced scan pattern with 16 scan lines distributedbetween four sub-scans (sub-scans 200-1, 200-2, 200-3, and 200-4). Inparticular embodiments, the scan lines 410 of an interlaced scan patternmay be distributed substantially evenly between the associatedsub-scans. As an example, for an interlaced scan pattern with 64 scanlines 410 and four sub-scans, each sub-scan may include 15-17 scan lines410. In particular embodiments, the scan lines 410 of an interlaced scanpattern may be distributed in a non-uniform manner between theassociated sub-scans. As an example, for an interlaced scan pattern with64 scan lines and four sub-scans, a first sub-scan may includeapproximately 32 scan lines, a second sub-scan may include approximately16 scan lines, and the remaining two sub-scans may each includeapproximately 8 scan lines.

In particular embodiments, each sub-scan of an interlaced scan patternmay be scanned in the same direction. As an example, each of the foursub-scans illustrated in FIGS. 29-32 may be scanned along the Θ_(y) scanaxis in a top-to-bottom direction (e.g., as illustrated by scan profile500 in FIG. 16). The scan lines of sub-scan 200-1 may be scanned inorder 410-1, 410-5, 410-9, 410-13. Then, the scan lines of sub-scan200-2 may be scanned in order 410-2, 410-6, 410-10, 410-14. Inparticular embodiments, sequential sub-scans of an interlaced scanpattern may be scanned in opposite directions (e.g., as illustrated bythe dual-direction scan profile 500 in FIG. 20). As an example,sub-scans 200-1 and 200-3 may be scanned along the Θ_(y) scan axis in atop-to-bottom direction, and sub-scans 200-2 and 200-4 may be scanned ina bottom-to-top direction. The scan lines of sub-scan 200-1 may bescanned in a top-down order (e.g., 410-1, 410-5, 410-9, 410-13), andthen, the scan lines of sub-scan 200-2 may be scanned in a bottom-uporder (e.g., 410-14, 410-10, 410-6, 410-2).

In particular embodiments, a lidar system 100 may include a light source110 configured to emit pulses of light and a scanner 120 configured toscan at least a portion of the emitted pulses of light along aninterlaced scan pattern. The scanner 120 may include an x-scan mirror(e.g., mirror 300-1 in FIG. 3 or 4) and a y-scan mirror (e.g., mirror300-2 in FIG. 3 or 4). The x-scan mirror may be configured to scanpulses of light substantially parallel to a Θ_(x) scan axis to producemultiple scan lines 410 of the interlaced scan pattern, where each scanline 410 is oriented substantially parallel to the Θ_(x) scan axis. They-scan mirror may be configured to distribute the scan lines 410 along aΘ_(y) scan axis that is substantially orthogonal to scan axis Θ_(x). Inparticular embodiments, the scan lines 410 (which may include a firstscan line, a second scan line, and a third scan line) may be distributedin an interlaced manner. As an example, the second scan line may bedisposed between the first and third scan lines, and the second scanline may be scanned after the first and third scan lines are scanned. Inthe example of FIGS. 27-28, scan line 410-2 of sub-scan 200B is locatedbetween the adjacent scan lines 410-1 and 410-3 of sub-scan 200A, andscan line 410-2 may be scanned after scan lines 410-1 and 410-3 arescanned. For example, a scanner 120 may be configured to scan acrossscan pattern 200A (which includes scan lines 410-1 and 410-3) prior toscanning across scan pattern 200B (which includes scan line 410-2).

In particular embodiments, an interlaced scan pattern may include twosub-scans having multiple even scan lines and multiple odd scan lines,respectively. The even and odd scan lines may be distributed in aninterlaced manner where: (1) each pair of adjacent even scan lines isseparated by an odd scan line; (2) each pair of adjacent odd scan linesis separated by an even scan line; and (3) the even scan lines arescanned after the odd scan lines are scanned. The interlaced scanpattern represented by FIGS. 27-28 includes the odd-numbered scan linesof sub-scan 200A and the even-numbered scan lines of sub-scan 200B. Thescan lines of sub-scans 200A and 200B are interlaced so that adjacentodd-numbered scan lines are separated by an even-numbered scan line, andadjacent even-numbered scan lines are separated by an odd-numbered scanline. For example, the adjacent odd-numbered scan lines 410-9 and 410-11of sub-scan 200A are separated by a dashed line which represents theeven-numbered scan line 410-10 of sub-scan 200B. Similarly, the adjacenteven-numbered scan lines 410-14 and 410-16 of sub-scan 200B areseparated by a dashed line which represents the odd-numbered scan line410-15 of sub-scan 200A.

In particular embodiments, a scanner 120 of a lidar system 100 may beconfigured to alternately scan sub-scan 200A and sub-scan 200B. Forexample, the scanner 120 may first scan the odd scan lines of sub-scan200A, and then, the scanner 120 may scan the even scan lines of sub-scan200B (or vice versa). Additionally, the scanner may continue thescanning sequence by repeatedly scanning the odd scan lines followed bythe even scan lines. In particular embodiments, the odd scan lines of aninterlaced scan pattern may be used to produce a firstpartial-resolution point cloud, and the even scan lines may be used toproduce a second partial-resolution point cloud. Additionally, the firstand second partial-resolution point clouds (or the pixels 210 associatedwith each of the point clouds) may be combined to produce afull-resolution point cloud. For example, the odd scan lines of sub-scan200A in FIG. 27 may be used to produce a first partial-resolution pointcloud, and the even scan lines of sub-scan 200B in FIG. 28 may be usedto produce a second partial-resolution point cloud. The twopartial-resolution point clouds (or the pixels 210 associated with eachof the point clouds) may be combined together to produce afull-resolution point cloud corresponding to scan pattern 200 in FIG.26. For an interlaced scan pattern with two sub-scans, eachpartial-resolution point cloud may have approximately one-half as manypixels 210 as the full-resolution point cloud. As an example, each scanline in FIGS. 27-28 may include approximately 1,000 pixels, and eachpartial-resolution point cloud may include approximately 8,000 pixels210. The full-resolution point cloud (which corresponds to scan pattern200 in FIG. 26) may include approximately 16,000 pixels.

In particular embodiments, an interlaced scan pattern that includes nsub-scans (where n is an integer greater than or equal to 2) may bereferred to as an n-fold interlaced scan pattern. Each sub-scan of ann-fold interlaced scan pattern may include two or more scan lines 410,and then sub-scans may be scanned in any suitable sequential manner.FIGS. 27-28 represent a 2-fold interlaced scan pattern (e.g., n=2) thatincludes two sub-scans (sub-scans 200A and 200B). Each sub-scan includeseight scan lines 410, and the sub-scans may be scanned in a sequentialmanner (e.g., sub-scan 200A is scanned prior to sub-scan 200B, or viceversa). FIGS. 29-32 represent a 4-fold interlaced scan pattern (e.g.,n=4) that includes four sub-scans (sub-scans 200-1, 200-2, 200-3, and200-4). Each sub-scan includes four scan lines 410, and the sub-scansmay be scanned in any suitable sequential order. As an example, thesub-scans may be scanned in order 200-1, 200-2, 200-3, 200-4, and thescanning sequence may continue by repeatedly scanning the four sub-scansin order.

In particular embodiments, for an n-fold interlaced scan pattern (whichincludes n sub-scans), adjacent scan lines of a particular sub-scan maybe separated from one another by (n−1) intermediate scan lines of theother sub-scans. The other sub-scans may include the (n−1) sub-scanswhich are different from the particular sub-scan, and the (n−1)intermediate scan lines located between the adjacent scan lines of theparticular sub-scan may include one scan line from each of the other(n−1) sub-scans. For example, for a 3-fold interlaced scan pattern(which includes three sub-scans), adjacent scan lines of each sub-scanmay be separated by two intermediate scan lines from the other twosub-scans. In particular embodiments, a pair of scan lines 410 in aparticular sub-scan may be referred to as being adjacent if there are noother scan lines from that particular sub-scan located between the pair.In particular embodiments, an intermediate scan line 410 may refer to ascan line associated with another sub-scan that is located betweenadjacent scan lines 410 of a particular sub-scan. A pair of adjacentscan lines 410 may have one or more intermediate scan lines 410 fromother sub-scans located between the pair. Sub-scan 200-1 in FIG. 29includes three pairs of adjacent scan lines: scan lines 410-1 and 410-5;scan lines 410-5 and 410-9; and scan lines 410-9 and 410-13. Each pairof adjacent scan lines in sub-scan 200-1 has three intermediate scanlines.

In FIGS. 27-28, which represent a 2-fold interlaced scan pattern,adjacent odd-numbered scan lines in sub-scan 200A are separated by oneintermediate scan line of sub-scan 200B. Similarly, each pair ofadjacent even-numbered scan lines in sub-scan 200B is separated by oneintermediate scan line of sub-scan 200A. In FIGS. 29-32, which representa 4-fold interlaced scan pattern, adjacent scan lines are separated fromone another by 3 intermediate scan lines of other sub-scans. Forexample, scan lines 410-1 and 410-5 of sub-scan 200-1 are separated by 3intermediate scan lines (represented by the three dashed lines betweenscan lines 410-1 and 410-5 in FIG. 29). Additionally, the threeintermediate scan lines include one scan line from each of the other 3sub-scans: scan line 410-2 from sub-scan 200-2; scan line 410-3 fromsub-scan 200-3; and scan line 410-4 from sub-scan 200-4. As anotherexample, scan lines 410-7 and 410-11 of sub-scan 200-3 are separated by3 intermediate scan lines from each of the other 3 sub-scans: scan line410-8 from sub-scan 200-4; scan line 410-9 from sub-scan 200-1; and scanline 410-10 from sub-scan 200-2.

In particular embodiments, an n-fold interlaced scan pattern may includea total of N scan lines 410, and each sub-scan of the n-fold interlacedscan pattern may include approximately N/n scan lines 410. As anexample, a 3-fold interlaced scan pattern may include a total of 64 scanlines 410, and the scan lines 410 may be allocated to each of the threesub-scans in a substantially uniform manner so that each sub-scanincludes approximately 21-22 scan lines 410. As another example, for a4-fold interlaced scan pattern with a total of 100 scan lines 410, eachsub-scan may include approximately 25 scan lines 410. FIGS. 29-32represent a 4-fold interlaced scan pattern with a total of 16 scanlines, and each sub-scan includes four scan lines 410.

In particular embodiments, an n-fold interlaced scan pattern may bescanned in a time period ΔT (where ΔT may be approximately equal to scantime τ_(scan) discussed above). As an example, a scanner 120 may scanacross an interlaced scan pattern every 100 ms, corresponding to a 10 Hzframe rate. For each scan of an interlaced scan pattern, a correspondingfull-resolution point cloud may be produced, and a series offull-resolution point clouds (associated with repeated scans of theinterlaced scan pattern) may be produced at a frequency of approximately1/ΔT. As an example, a scanner 120 may scan across an interlaced scanpattern in a 100-ms time period, and full-resolution point cloudscorresponding to each scan of the interlaced scan patterns may beproduced at a frequency (or, frame rate) of approximately 10 Hz. Inparticular embodiments, for an n-fold interlaced scan pattern that isscanned in a time period ΔT, partial-resolution point clouds based oneach of the n sub-scans of the interlaced scan pattern may be producedat a frequency of approximately n/ΔT. As an example, for a 4-foldinterlaced scan pattern that is scanned in a 100-ms time period,partial-resolution point clouds based on each of the four sub-scans maybe produced approximately every 25 ms, corresponding to a frequency ofapproximately 40 Hz. In particular embodiments, for an n-fold interlacedscan pattern, partial-resolution point clouds may be produced at a framerate that is approximately n times higher than the frame rate of thecorresponding full-resolution point clouds.

In particular embodiments, a scanner 120 may be configured to scanpulses of light emitted by light source 110 along a non-interlaced scanpattern as well as along an interlaced scan pattern. As an example, ascanner 120 may be configured to scan along a non-interlaced scanpattern represented by scan pattern 200 in FIG. 26. Additionally, thescanner 120 may be configured to scan along an interlaced scan patternrepresented by sub-scans 200-1, 200-2, 200-3, and 200-4 illustrated inFIGS. 29-32. In particular embodiments, an interlaced scan pattern mayprovide a higher frame rate than a non-interlaced scan pattern. As anexample, a non-interlaced scan pattern may produce full-resolution pointclouds at a frame rate of 1/ΔT, and a corresponding n-fold interlacedscan pattern may produce partial-resolution point clouds at a frame ratethat is approximately n-times higher (e.g., n/ΔT). An interlaced scanpattern represented by the four sub-scans in FIGS. 29-32 may producepoint clouds at a frame rate that is approximately four times higherthan a non-interlaced scan pattern based on FIG. 26. Thepartial-resolution point clouds produced by an interlaced scan patternmay have lower resolution (e.g., a lower number of pixels 210 or a lowerdensity of pixels 210) than the full-resolution point clouds produced bya non-interlaced scan pattern, but the partial-resolution point cloudsmay allow a lidar system 100 to monitor or track objects at a higherframe rate. Additionally, a set of n successive partial-resolution pointclouds may be combined to produce a full-resolution point cloud havingapproximately the same resolution and frame rate as a full-resolutionpoint cloud produced using a non-interlaced scan pattern.

In particular embodiments, a scanner 120 in a lidar system 100 may beconfigured to switch from scanning along a non-interlaced scan patternto scanning along an interlaced scan pattern (or vice versa). As anexample, lidar system 100 may be coupled to or may include a processor(e.g., controller 150) configured to send an instruction that results inthe scanner 120 switching from scanning along a non-interlaced scanpattern to scanning along an interlaced scan pattern. In particularembodiments, switching from a non-interlaced scan pattern to aninterlaced scan pattern (or vice versa) may be based at least in part ona driving condition of a vehicle in which lidar system 100 is operating.As an example, a driving condition may include determining that a target130 is within a particular threshold distance of the vehicle or lidarsystem 100. The target 130 may be a bicycle located within 50 meters ofthe vehicle, and the lidar system may switch to scanning with an n-foldinterlaced scan pattern so that information about the bicycle (e.g.,location, direction, or speed) may be provided at a n-times higher rate.As another example, a driving condition may include determining that atarget 130 has a speed with respect to the lidar system 100 that isabove a particular threshold speed. The target 130 may be a vehiclemoving at greater than 50 miles per hour with respect to the lidarsystem 100, and scanning with an interlaced scan pattern may provideinformation about the vehicle (e.g., location, direction, or speed) at ahigher rate than a non-interlaced scan pattern.

FIG. 33 illustrates an example method 1000 for scanning along aninterlaced scan pattern. The method may begin at step 1010, where pulsesof light may be emitted by a light source 110 of a lidar system 100. Asan example, light source 110 may be a pulsed laser that emits pulseswith a 0.5-5 ns duration and a wavelength of 1400-1600 nm. At step 1020,at least a portion of the emitted pulses of light may be scanned alongan interlaced scan pattern. The pulses may be scanned substantiallyparallel to scan axis Θ_(x) to produce multiple scan lines 410 of theinterlaced scan pattern, where each scan line 410 is orientedsubstantially parallel to scan axis Θ_(x), and the scan lines 410 may bedistributed along scan axis Θ_(y) in an interlaced manner. For example,the scan lines 410 may include a first scan line, a second scan line,and a third scan line. The second scan line may be an intermediate scanline disposed between the first and third scan lines, and the secondscan line may be scanned after the first and third scan lines arescanned. At step 1030, at least a portion of the pulses of lightscattered by a target 130 may be detected, at which point the method mayend. As an example, pulses of light scattered by a target 130 may bedetected by an APD that is part of a receiver 140.

FIG. 34 illustrates an example computer system 600. In particularembodiments, one or more computer systems 600 may perform one or moresteps of one or more methods described or illustrated herein. Inparticular embodiments, one or more computer systems 600 may providefunctionality described or illustrated herein. In particularembodiments, software running on one or more computer systems 600 mayperform one or more steps of one or more methods described orillustrated herein or may provide functionality described or illustratedherein. Particular embodiments may include one or more portions of oneor more computer systems 600. In particular embodiments, a computersystem may be referred to as a computing device, a computing system, acomputer, a general-purpose computer, or a data-processing apparatus.Herein, reference to a computer system may encompass one or morecomputer systems, where appropriate.

Computer system 600 may take any suitable physical form. As an example,computer system 600 may be an embedded computer system, a system-on-chip(SOC), a single-board computer system (SBC), a desktop computer system,a laptop or notebook computer system, a mainframe, a mesh of computersystems, a server, a tablet computer system, or any suitable combinationof two or more of these. As another example, all or part of computersystem 600 may be combined with, coupled to, or integrated into avariety of devices, including, but not limited to, a camera, camcorder,personal digital assistant (PDA), mobile telephone, smartphone,electronic reading device (e.g., an e-reader), game console, smartwatch, clock, calculator, television monitor, flat-panel display,computer monitor, vehicle display (e.g., odometer display or dashboarddisplay), vehicle navigation system, lidar system, ADAS, autonomousvehicle, autonomous-vehicle driving system, cockpit control, camera viewdisplay (e.g., display of a rear-view camera in a vehicle), eyewear, orhead-mounted display. Where appropriate, computer system 600 may includeone or more computer systems 600; be unitary or distributed; spanmultiple locations; span multiple machines; span multiple data centers;or reside in a cloud, which may include one or more cloud components inone or more networks. Where appropriate, one or more computer systems600 may perform without substantial spatial or temporal limitation oneor more steps of one or more methods described or illustrated herein. Asan example, one or more computer systems 600 may perform in real time orin batch mode one or more steps of one or more methods described orillustrated herein. One or more computer systems 600 may perform atdifferent times or at different locations one or more steps of one ormore methods described or illustrated herein, where appropriate.

As illustrated in the example of FIG. 34, computer system 600 mayinclude a processor 610, memory 620, storage 630, an input/output (I/O)interface 640, a communication interface 650, or a bus 660. Computersystem 600 may include any suitable number of any suitable components inany suitable arrangement.

In particular embodiments, processor 610 may include hardware forexecuting instructions, such as those making up a computer program. Asan example, to execute instructions, processor 610 may retrieve (orfetch) the instructions from an internal register, an internal cache,memory 620, or storage 630; decode and execute them; and then write oneor more results to an internal register, an internal cache, memory 620,or storage 630. In particular embodiments, processor 610 may include oneor more internal caches for data, instructions, or addresses. Processor610 may include any suitable number of any suitable internal caches,where appropriate. As an example, processor 610 may include one or moreinstruction caches, one or more data caches, or one or more translationlookaside buffers (TLBs). Instructions in the instruction caches may becopies of instructions in memory 620 or storage 630, and the instructioncaches may speed up retrieval of those instructions by processor 610.Data in the data caches may be copies of data in memory 620 or storage630 for instructions executing at processor 610 to operate on; theresults of previous instructions executed at processor 610 for access bysubsequent instructions executing at processor 610 or for writing tomemory 620 or storage 630; or other suitable data. The data caches mayspeed up read or write operations by processor 610. The TLBs may speedup virtual-address translation for processor 610. In particularembodiments, processor 610 may include one or more internal registersfor data, instructions, or addresses. Processor 610 may include anysuitable number of any suitable internal registers, where appropriate.Where appropriate, processor 610 may include one or more arithmeticlogic units (ALUs); may be a multi-core processor; or may include one ormore processors 610.

In particular embodiments, memory 620 may include main memory forstoring instructions for processor 610 to execute or data for processor610 to operate on. As an example, computer system 600 may loadinstructions from storage 630 or another source (such as, for example,another computer system 600) to memory 620. Processor 610 may then loadthe instructions from memory 620 to an internal register or internalcache. To execute the instructions, processor 610 may retrieve theinstructions from the internal register or internal cache and decodethem. During or after execution of the instructions, processor 610 maywrite one or more results (which may be intermediate or final results)to the internal register or internal cache. Processor 610 may then writeone or more of those results to memory 620. One or more memory buses(which may each include an address bus and a data bus) may coupleprocessor 610 to memory 620. Bus 660 may include one or more memorybuses. In particular embodiments, one or more memory management units(MMUs) may reside between processor 610 and memory 620 and facilitateaccesses to memory 620 requested by processor 610. In particularembodiments, memory 620 may include random access memory (RAM). This RAMmay be volatile memory, where appropriate. Where appropriate, this RAMmay be dynamic RAM (DRAM) or static RAM (SRAM). Memory 620 may includeone or more memories 620, where appropriate.

In particular embodiments, storage 630 may include mass storage for dataor instructions. As an example, storage 630 may include a hard diskdrive (HDD), a floppy disk drive, flash memory, an optical disc, amagneto-optical disc, magnetic tape, or a Universal Serial Bus (USB)drive or a combination of two or more of these. Storage 630 may includeremovable or non-removable (or fixed) media, where appropriate. Storage630 may be internal or external to computer system 600, whereappropriate. In particular embodiments, storage 630 may be non-volatile,solid-state memory. In particular embodiments, storage 630 may includeread-only memory (ROM). Where appropriate, this ROM may be mask ROM(MROM), programmable ROM (PROM), erasable PROM (EPROM), electricallyerasable PROM (EEPROM), flash memory, or a combination of two or more ofthese. Storage 630 may include one or more storage control unitsfacilitating communication between processor 610 and storage 630, whereappropriate. Where appropriate, storage 630 may include one or morestorages 630.

In particular embodiments, I/O interface 640 may include hardware,software, or both, providing one or more interfaces for communicationbetween computer system 600 and one or more I/O devices. Computer system600 may include one or more of these I/O devices, where appropriate. Oneor more of these I/O devices may enable communication between a personand computer system 600. As an example, an I/O device may include akeyboard, keypad, microphone, monitor, mouse, printer, scanner, speaker,camera, stylus, tablet, touch screen, trackball, another suitable I/Odevice, or any suitable combination of two or more of these. An I/Odevice may include one or more sensors. Where appropriate, I/O interface640 may include one or more device or software drivers enablingprocessor 610 to drive one or more of these I/O devices. I/O interface640 may include one or more I/O interfaces 640, where appropriate.

In particular embodiments, communication interface 650 may includehardware, software, or both providing one or more interfaces forcommunication (such as, for example, packet-based communication) betweencomputer system 600 and one or more other computer systems 600 or one ormore networks. As an example, communication interface 650 may include anetwork interface controller (NIC) or network adapter for communicatingwith an Ethernet or other wire-based network or a wireless NIC (WNIC); awireless adapter for communicating with a wireless network, such as aWI-FI network; or an optical transmitter (e.g., a laser or alight-emitting diode) or an optical receiver (e.g., a photodetector) forcommunicating using fiber-optic communication or free-space opticalcommunication. Computer system 600 may communicate with an ad hocnetwork, a personal area network (PAN), an in-vehicle network (IVN), alocal area network (LAN), a wide area network (WAN), a metropolitan areanetwork (MAN), or one or more portions of the Internet or a combinationof two or more of these. One or more portions of one or more of thesenetworks may be wired or wireless. As an example, computer system 600may communicate with a wireless PAN (WPAN) (such as, for example, aBLUETOOTH WPAN), a WI-FI network, a Worldwide Interoperability forMicrowave Access (WiMAX) network, a cellular telephone network (such as,for example, a Global System for Mobile Communications (GSM) network),or other suitable wireless network or a combination of two or more ofthese. As another example, computer system 600 may communicate usingfiber-optic communication based on 100 Gigabit Ethernet (100 GbE), 10Gigabit Ethernet (10 GbE), or Synchronous Optical Networking (SONET).Computer system 600 may include any suitable communication interface 650for any of these networks, where appropriate. Communication interface650 may include one or more communication interfaces 650, whereappropriate.

In particular embodiments, bus 660 may include hardware, software, orboth coupling components of computer system 600 to each other. As anexample, bus 660 may include an Accelerated Graphics Port (AGP) or othergraphics bus, a controller area network (CAN) bus, an Enhanced IndustryStandard Architecture (EISA) bus, a front-side bus (FSB), aHYPERTRANSPORT (HT) interconnect, an Industry Standard Architecture(ISA) bus, an INFINIBAND interconnect, a low-pin-count (LPC) bus, amemory bus, a Micro Channel Architecture (MCA) bus, a PeripheralComponent Interconnect (PCI) bus, a PCI-Express (PCIe) bus, a serialadvanced technology attachment (SATA) bus, a Video Electronics StandardsAssociation local bus (VLB), or another suitable bus or a combination oftwo or more of these. Bus 660 may include one or more buses 660, whereappropriate.

In particular embodiments, various modules, circuits, systems, methods,or algorithm steps described in connection with the implementationsdisclosed herein may be implemented as electronic hardware, computersoftware, or any suitable combination of hardware and software. Inparticular embodiments, computer software (which may be referred to assoftware, computer-executable code, computer code, a computer program,computer instructions, or instructions) may be used to perform variousfunctions described or illustrated herein, and computer software may beconfigured to be executed by or to control the operation of computersystem 600. As an example, computer software may include instructionsconfigured to be executed by processor 610. In particular embodiments,owing to the interchangeability of hardware and software, the variousillustrative logical blocks, modules, circuits, or algorithm steps havebeen described generally in terms of functionality. Whether suchfunctionality is implemented in hardware, software, or a combination ofhardware and software may depend upon the particular application ordesign constraints imposed on the overall system.

In particular embodiments, a computing device may be used to implementvarious modules, circuits, systems, methods, or algorithm stepsdisclosed herein. As an example, all or part of a module, circuit,system, method, or algorithm disclosed herein may be implemented orperformed by a general-purpose single- or multi-chip processor, adigital signal processor (DSP), an ASIC, a FPGA, any other suitableprogrammable-logic device, discrete gate or transistor logic, discretehardware components, or any suitable combination thereof. Ageneral-purpose processor may be a microprocessor, or, any conventionalprocessor, controller, microcontroller, or state machine. A processormay also be implemented as a combination of computing devices, e.g., acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

In particular embodiments, one or more implementations of the subjectmatter described herein may be implemented as one or more computerprograms (e.g., one or more modules of computer-program instructionsencoded or stored on a computer-readable non-transitory storage medium).As an example, the steps of a method or algorithm disclosed herein maybe implemented in a processor-executable software module which mayreside on a computer-readable non-transitory storage medium. Inparticular embodiments, a computer-readable non-transitory storagemedium may include any suitable storage medium that may be used to storeor transfer computer software and that may be accessed by a computersystem. Herein, a computer-readable non-transitory storage medium ormedia may include one or more semiconductor-based or other integratedcircuits (ICs) (such, as for example, field-programmable gate arrays(FPGAs) or application-specific ICs (ASICs)), hard disk drives (HDDs),hybrid hard drives (HHDs), optical discs (e.g., compact discs (CDs),CD-ROM, digital versatile discs (DVDs), blue-ray discs, or laser discs),optical disc drives (ODDs), magneto-optical discs, magneto-opticaldrives, floppy diskettes, floppy disk drives (FDDs), magnetic tapes,flash memories, solid-state drives (SSDs), RAM, RAM-drives, ROM, SECUREDIGITAL cards or drives, any other suitable computer-readablenon-transitory storage media, or any suitable combination of two or moreof these, where appropriate. A computer-readable non-transitory storagemedium may be volatile, non-volatile, or a combination of volatile andnon-volatile, where appropriate.

In particular embodiments, certain features described herein in thecontext of separate implementations may also be combined and implementedin a single implementation. Conversely, various features that aredescribed in the context of a single implementation may also beimplemented in multiple implementations separately or in any suitablesub-combination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination may in some cases be excisedfrom the combination, and the claimed combination may be directed to asub-combination or variation of a sub-combination.

While operations may be depicted in the drawings as occurring in aparticular order, this should not be understood as requiring that suchoperations be performed in the particular order shown or in sequentialorder, or that all operations be performed. Further, the drawings mayschematically depict one more example processes or methods in the formof a flow diagram or a sequence diagram. However, other operations thatare not depicted may be incorporated in the example processes or methodsthat are schematically illustrated. For example, one or more additionaloperations may be performed before, after, simultaneously with, orbetween any of the illustrated operations. Moreover, one or moreoperations depicted in a diagram may be repeated, where appropriate.Additionally, operations depicted in a diagram may be performed in anysuitable order. Furthermore, although particular components, devices, orsystems are described herein as carrying out particular operations, anysuitable combination of any suitable components, devices, or systems maybe used to carry out any suitable operation or combination ofoperations. In certain circumstances, multitasking or parallelprocessing operations may be performed. Moreover, the separation ofvarious system components in the implementations described herein shouldnot be understood as requiring such separation in all implementations,and it should be understood that the described program components andsystems may be integrated together in a single software product orpackaged into multiple software products.

Various embodiments have been described in connection with theaccompanying drawings. However, it should be understood that the figuresmay not necessarily be drawn to scale. As an example, distances orangles depicted in the figures are illustrative and may not necessarilybear an exact relationship to actual dimensions or layout of the devicesillustrated.

The scope of this disclosure encompasses all changes, substitutions,variations, alterations, and modifications to the example embodimentsdescribed or illustrated herein that a person having ordinary skill inthe art would comprehend. The scope of this disclosure is not limited tothe example embodiments described or illustrated herein. Moreover,although this disclosure describes or illustrates respective embodimentsherein as including particular components, elements, functions,operations, or steps, any of these embodiments may include anycombination or permutation of any of the components, elements,functions, operations, or steps described or illustrated anywhere hereinthat a person having ordinary skill in the art would comprehend.

The term “or” as used herein is to be interpreted as an inclusive ormeaning any one or any combination, unless expressly indicated otherwiseor indicated otherwise by context. Therefore, herein, the expression “Aor B” means “A, B, or both A and B.” As another example, herein, “A, Bor C” means at least one of the following: A; B; C; A and B; A and C; Band C; A, B and C. An exception to this definition will occur if acombination of elements, devices, steps, or operations is in some wayinherently mutually exclusive.

As used herein, words of approximation such as, without limitation,“approximately, “substantially,” or “about” refer to a condition thatwhen so modified is understood to not necessarily be absolute or perfectbut would be considered close enough to those of ordinary skill in theart to warrant designating the condition as being present. The extent towhich the description may vary will depend on how great a change can beinstituted and still have one of ordinary skill in the art recognize themodified feature as having the required characteristics or capabilitiesof the unmodified feature. In general, but subject to the precedingdiscussion, a numerical value herein that is modified by a word ofapproximation such as “approximately” may vary from the stated value by±0.5%, ±1%, ±2%, ±3%, ±4%, ±5%, ±10%, ±12%, or ±15%.

As used herein, the terms “first,” “second,” “third,” etc. may be usedas labels for nouns that they precede, and these terms may notnecessarily imply a particular ordering (e.g., a particular spatial,temporal, or logical ordering). As an example, a system may be describedas determining a “first result” and a “second result,” and the terms“first” and “second” may not necessarily imply that the first result isdetermined before the second result.

As used herein, the terms “based on” and “based at least in part on” maybe used to describe or present one or more factors that affect adetermination, and these terms may not exclude additional factors thatmay affect a determination. A determination may be based solely on thosefactors which are presented or may be based at least in part on thosefactors. The phrase “determine A based on B” indicates that B is afactor that affects the determination of A. In some instances, otherfactors may also contribute to the determination of A. In otherinstances, A may be determined based solely on B.

What is claimed is:
 1. A lidar system comprising: a light source configured to emit pulses of light; a scanner configured to scan at least a portion of the emitted pulses of light along an interlaced scan pattern, wherein the scanner comprises: a first scanning mirror configured to scan the portion of the emitted pulses of light substantially parallel to a first scan axis to produce a plurality of scan lines of the interlaced scan pattern, wherein each scan line is oriented substantially parallel to the first scan axis; and a second scanning mirror configured to distribute the scan lines along a second scan axis that is substantially orthogonal to the first scan axis, wherein the scan lines are distributed in an interlaced manner, wherein the interlaced scan pattern is an n-fold interlaced scan pattern comprising n sub-scans, wherein: n is an integer greater than or equal to 2; each sub-scan comprises two or more of the scan lines of the interlaced scan pattern; the n sub-scans are scanned sequentially wherein a first sub-scan of the n sub-scans is scanned prior to a second sub-scan; adjacent scan lines of a particular sub-scan are separated from one another by (n−1) intermediate scan lines of other sub-scans; the n-fold interlaced scan pattern is scanned in a time period ΔT; full-resolution point clouds based on the n-fold interlaced scan pattern are produced at a frequency of approximately 1/ΔT; and partial-resolution point clouds based on each of the sub-scans are produced at a frequency of approximately n/ΔT; and a receiver configured to detect at least a portion of the scanned pulses of light scattered by a target located a distance from the lidar system.
 2. The lidar system of claim 1, wherein: n=2; the interlaced scan pattern is a 2-fold interlaced scan pattern, wherein the first sub-scan comprises a plurality of even scan lines and the second sub-scan comprises a plurality of odd scan lines; each pair of adjacent even scan lines is separated by an odd scan line; and each pair of adjacent odd scan lines is separated by an even scan line.
 3. The lidar system of claim 2, wherein: the odd scan lines are used to produce a first partial-resolution point cloud; the even scan lines are used to produce a second partial-resolution point cloud; and the first and second partial-resolution point clouds are combined to produce a full-resolution point cloud.
 4. The lidar system of claim 1, wherein: the other sub-scans comprise (n−1) sub-scans of the n sub-scans which are different from the particular sub-scan; and the (n−1) intermediate scan lines located between the adjacent scan lines of the particular sub-scan comprise one scan line from each of the other sub-scans.
 5. The lidar system of claim 1, wherein: the interlaced scan pattern comprises N scan lines; and each sub-scan comprises approximately N/n scan lines.
 6. The lidar system of claim 1, wherein: n=2; and the interlaced scan pattern is a 2-fold interlaced scan pattern comprising the first sub-scan and the second sub-scan.
 7. The lidar system of claim 1, wherein: n=4; and the interlaced scan pattern is a 4-fold interlaced scan pattern comprising four sub-scans.
 8. The lidar system of claim 1, wherein the scanner is further configured to scan the portion of the emitted pulses of light along a non-interlaced scan pattern, wherein the scan lines are scanned sequentially, wherein: the scan lines comprise a first scan line, a second scan line, and a third scan line, wherein the second scan line is disposed between the first and third scan lines; and during the scan of the non-interlaced scan pattern, the second scan line is scanned after the first scan line is scanned and the third scan line is scanned after the second scan line is scanned.
 9. The lidar system of claim 8, wherein the interlaced scan pattern is configured to provide a higher frame rate than the non-interlaced scan pattern.
 10. The lidar system of claim 8, further comprising a processor configured to instruct the scanner to switch from scanning along the non-interlaced scan pattern to scanning along the interlaced scan pattern.
 11. The lidar system of claim 10, wherein the processor is configured to instruct the scanner to switch from the non-interlaced scan pattern to the interlaced scan pattern based at least in part on a driving condition of a vehicle in which the lidar system is operating, wherein the driving condition comprises determining that the target is within a particular threshold distance of the lidar system or that the target has a speed with respect to the lidar system above a particular threshold speed.
 12. The lidar system of claim 1, wherein: the first scanning mirror is driven repeatedly in a back-and-forth motion by a galvanometer scanner; and each scan line corresponds to a single forward or backward motion of the galvanometer scanner.
 13. The lidar system of claim 1, wherein the first scanning mirror is a polygon mirror comprising two or more reflective surfaces, wherein: the polygon mirror is configured to continuously rotate in one direction about a rotation axis of the polygon mirror; and the portion of the emitted pulses of light are reflected sequentially from the reflective surfaces as the polygon mirror is rotated, resulting in the portion of the emitted pulses of light being scanned substantially parallel to the first scan axis to produce the plurality of scan lines, wherein each scan line corresponds to a reflection from one of the reflective surfaces.
 14. The lidar system of claim 1, further comprising a processor configured to determine the distance from the lidar system to the target based at least in part on a round-trip time of flight for an emitted pulse of light to travel from the lidar system to the target and back to the lidar system.
 15. The lidar system of claim 1, wherein the interlaced scan pattern is a dual-direction interlaced scan pattern wherein the first sub-scan is scanned in a first direction and the second sub-scan is scanned in a second direction opposite the first direction.
 16. The lidar system of claim 15, wherein the first direction is a top-to-bottom direction and the second direction is a bottom-to-top direction.
 17. The lidar system of claim 1, wherein: the time period ΔT is approximately 100 ms; the full-resolution point clouds are produced at a frequency of approximately 10 Hz; n is equal to 4, so that the interlaced scan pattern is a 4-fold interlaced scan pattern comprising 4 sub-scans; and partial-resolution point clouds based on each of the sub-scans are produced at a frequency of approximately 40 Hz.
 18. A method comprising: emitting, by a light source of a lidar system, pulses of light; scanning, by a scanner of the lidar system, at least a portion of the emitted pulses of light along an interlaced scan pattern, comprising: scanning the portion of the emitted pulses of light substantially parallel to a first scan axis to produce a plurality of scan lines of the interlaced scan pattern, wherein each scan line is oriented substantially parallel to the first scan axis; and distributing the scan lines along a second scan axis that is substantially orthogonal to the first scan axis, wherein the scan lines are distributed in an interlaced manner, wherein the interlaced scan pattern is an n-fold interlaced scan pattern comprising n sub-scans, wherein: n is an integer greater than or equal to 2; each sub-scan comprises two or more of the scan lines of the interlaced scan pattern; the n sub-scans are scanned sequentially wherein a first sub-scan of the n sub-scans is scanned prior to a second sub-scan; adjacent scan lines of a particular sub-scan are separated from one another by (n−1) intermediate scan lines of other sub-scans; and the n-fold interlaced scan pattern is scanned in a time period ΔT; detecting, by a receiver of the lidar system, at least a portion of the scanned pulses of light scattered by a target located a distance from the lidar system; producing, by a processor of the lidar system, full-resolution point clouds based on the n-fold interlaced scan pattern at a frequency of approximately 1/ΔT; and producing, by the processor, partial-resolution point clouds based on each of the sub-scans at a frequency of approximately n/ΔT.
 19. The method of claim 18, further comprising scanning, by the scanner, the portion of the emitted pulses of light along a non-interlaced scan pattern, wherein the scan lines are scanned sequentially, wherein: the scan lines comprise a first scan line, a second scan line, and a third scan line, wherein the second scan line is disposed between the first and third scan lines; and during the scan of the non-interlaced scan pattern, the second scan line is scanned after the first scan line is scanned and the third scan line is scanned after the second scan line is scanned.
 20. The method of claim 18, wherein: n=2; the interlaced scan pattern is a 2-fold interlaced scan pattern, wherein the first sub-scan comprises a plurality of even scan lines and the second sub-scan comprises a plurality of odd scan lines; each pair of adjacent even scan lines is separated by an odd scan line; and each pair of adjacent odd scan lines is separated by an even scan line. 